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The first recorded aircraft hijack took place on February 21, 1931, in Arequipa, Peru. Byron Richards, flying a Ford Tri-Motor, was approached on the ground by armed revolutionaries. He refused to fly them anywhere during a 10-day standoff. Richards was informed that the revolution was successful and he could be freed in return for flying one of the men to Lima.
The following year, in September 1932, a Sikorsky S-38 with registration P-BDAD, registered to Nyrba do Brasil, was seized in the company's hangar by three men, who took a hostage. Despite having no flying experience, they managed to take off. However, the aircraft crashed in São João de Meriti, killing the four men. Apparently, the hijack was related to the events of the Constitutionalist Revolution in São Paulo; it is considered to be the first hijack that took place in Brazil.
On October 28, 1939, the first murder on a plane took place in Brookfield, Missouri, US. The victim was Carl Bivens, a flight instructor, who was teaching a man named Earnest P. "Larry" Pletch. While airborne in a Taylor Cub monoplane, Pletch shot Bivens twice in the back of the head. Pletch later told prosecutors, "Carl was telling me I had a natural ability and I should follow that line", adding, "I had a revolver in my pocket and without saying a word to him, I took it out of my overalls and I fired a bullet into the back of his head. He never knew what struck him." The "Chicago Daily Tribune" stated it was one of the most spectacular crimes of the 20th century. Pletch pleaded guilty and was sentenced to life in prison. However, he was released on March 1, 1957, after serving 17 years, and lived until June 2001.
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In 1942 near Malta, two New Zealanders, a South African, and an Englishman achieved the first confirmed in-air hijack when they overpowered their captors aboard an Italian seaplane that was flying them to a prisoner-of-war camp. As they approached an Allied base, they were strafed by Supermarine Spitfires unaware of the aircraft's true operators and forced to land on the water. However, all on board survived to be picked up by a British boat.
In the years following World War II, Philip Baum, an aviation security expert, suggested that the development of a rebellious youth "piggybacking on to any cause which challenged the status quo or acted in support of those deemed oppressed" may have been a contributor to attacks against the aviation field. The first hijacking of a commercial flight occurred on the Cathay Pacific "Miss Macao" on July 16, 1948. After this incident and others in the 1950s, airlines recommended that flight crews comply with the hijackers' demands rather than risk a violent confrontation. There were also various hijacking incidents and assaults on planes in China and the Middle East. The forced landing by the Israeli Air Force of a Syrian Airlines plane in December 1954 has been described by multiple writers as a state-sponsored hijacking.
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On 23 July 1956, in the Hungarian People's Republic, seven passengers hijacked a domestic flight of Malév Hungarian Airlines, a Lisunov Li-2 (registration HA-LIG), to escape from behind the Iron Curtain, and flew it to West Germany. The aircraft landed safely at Ingolstadt Air Base without injuries.
An aircraft belonging to the airline Lloyd Aereo Boliviano was hijacked in Bolivia on September 26, 1956. The DC-4 was carrying 47 prisoners who were being transported from Santa Cruz, Bolivia, to El Alto, in La Paz. A political group was waiting to take them to a concentration camp located in Carahuara de Carangas, Oruro. The 47 prisoners overpowered the crew and gained control of the aircraft while airborne and diverted the plane to Tartagal, Argentina. Prisoners took control of the aircraft and received instructions to again fly to Salta, Argentina, as the airfield in Tartagal was not big enough. Upon landing, they told the government of the injustice they were subjected to, and received political asylum.
On October 22, 1956, French forces hijacked a Moroccan airplane carrying leaders of the Algerian National Liberation Front (FLN) during the ongoing Algerian War. The plane, which was carrying Ahmed Ben Bella, Hocine Aït Ahmed, and Mohamed Boudiaf, was destined to leave from Palma de Mallorca for Tunis where the FLN leaders were to conference with Prime Minister Habib Bourguiba, but French forces redirected the flight to occupied Algiers, where the FLN leaders were arrested.
1958–1979.
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Between 1958 and 1967, there were approximately 40 hijackings worldwide. Beginning in 1958, hijackings from Cuba to other destinations started to occur; in 1961, hijackings from other destinations to Cuba became prevalent. The first happened on May 1, 1961, on a flight from Miami to Key West. The perpetrator, armed with a knife and gun, forced the captain to land in Cuba.
Australia was relatively untouched by the threat of hijackings until July 19, 1960. On that evening, a 22-year-old Russian man attempted to divert Trans Australia Airlines Flight 408 to Darwin or Singapore. The crew were able to subdue the man after a brief struggle.
According to the FAA, in the 1960s, there were 100 attempts of hijackings involving U.S. aircraft: 77 successful and 23 unsuccessful. Recognizing the danger early, the FAA issued a directive on July 28, 1961, which prohibits unauthorized persons from carrying concealed firearms and interfering with crew member duties. The Federal Aviation Act of 1958 was amended to impose severe penalties for those seizing control of a commercial aircraft. Airlines could also refuse to transport passengers who were likely to cause danger. That same year, the FAA and Department of Justice created the Peace Officers Program which put trained marshals on flights. A few years later, on May 7, 1964, the FAA adopted a rule requiring that cockpit doors on commercial aircraft be kept locked at all times.
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In a five-year period (1968–1972) the world experienced 326 hijack attempts, or one every 5.6 days. The incidents were frequent and often just an inconvenience, which resulted in television shows creating parodies. "Time" magazine even ran a lighthearted comedy piece called "What to Do When the Hijacker Comes". Most incidents occurred in the United States. There were two distinct types: hijackings for transportation elsewhere and hijackings for extortion with the threat of harm.
Between 1968 and 1972, there were 90 recorded transport attempts to Cuba. In contrast, there were 26 extortion attempts (see table on the right). The longest and first transcontinental (Los Angeles, Denver, New York, Bangor, Shannon and Rome) hijacking from the US started on 31 October 1969.
The Eastern Air Lines Shuttle Flight 1320 on May 17, 1970, witnessed the first fatality in the course of a U.S. hijacking.
Incidents also became problematic outside of the U.S. For instance, in 1968, El Al Flight 426 was seized by Popular Front for the Liberation of Palestine (PFLP) militants on 23 July, an incident which lasted 40 days, making it one of the longest. This record was later beaten in 1999.
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As a result of the evolving threat, President Nixon issued a directive in 1970 to promote security at airports, electronic surveillance and multilateral agreements for tackling the problem.
The International Civil Aviation Organization (ICAO) issued a report on aircraft hijacking in July 1970. Beginning in 1969 until the end of June 1970, there were 118 incidents of unlawful seizure of aircraft and 14 incidents of sabotage and armed attacks against civil aviation. This involved airlines of 47 countries and more than 7,000 passengers. In this period, 96 people were killed and 57 were injured as a result of hijacking, sabotage and armed attacks.
The ICAO stated that this is not isolated to one nation or one region, but a worldwide issue to the safe growth of international civil aviation. Incidents also became notoriousin 1971, a man known as D. B. Cooper hijacked a plane and extorted US$200,000 in ransom before parachuting over Oregon. He was never identified.
On August 20, 1971, a Pakistan Air Force T-33 military plane was hijacked prior the Indo-Pakistani war of 1971 in Karachi. Lieutenant Matiur Rahman attacked Officer Rashid Minhas and attempted to land in India. Minhas deliberately crashed the plane into the ground near Thatta to prevent the diversion.
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Countries around the world continued their efforts to tackle crimes committed on-board planes. The Tokyo Convention, drafted in 1958, established an agreement between signatories that the "state in which the aircraft is registered is competent to exercise jurisdiction over crimes committed on board that aircraft while it is in flight". While the Convention does not make hijacking an international crime, it does contain provisions which obligate the country in which a hijacked aircraft lands to restore the aircraft to its responsible owner, and allow the passengers and crew to continue their journey. The Convention came into force in December 1969.
A year later, in December 1970, the Hague Convention was drafted which punishes hijackers, enabling each state to prosecute a hijacker if that state does not extradite them, and to deprive them from asylum from prosecution.
On December 5, 1972, the FAA issued emergency rules requiring all passengers and their carry-on baggage to be screened. Airports slowly implemented walk-through metal detectors, hand-searches and X-ray machines, to prohibit weapons and explosive devices. These rules came into effect on January 5, 1973, and were welcomed by most of the public. In 1974, Congress enacted a statute which provided for the death penalty for acts of aircraft piracy resulting in death. Between 1968 and 1977, there were approximately 41 hijackings per year.
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In the 1970s, in pursuit of their demands for Croatia's independence from the Socialist Republic of Yugoslavia, Croatian nationalists hijacked several civilian airliners, such as Scandinavian Airlines System Flight 130 and TWA Flight 355.
1980–2000.
By 1980, airport screening and greater cooperation from the international community led to fewer successful hijackings; the number of events had significantly dropped below the 1968 level. Between 1978 and 1988, there were roughly 26 incidents of hijackings a year. A new threat emerged in the 1980s: organised terrorists destroying aircraft to draw attention. For instance, terrorist groups were responsible for the bombing of Air India Flight 182 over the Irish coast. In 1988, Pan Am Flight 103 was bombed flying over Scotland. Terrorist activity which included hijack attempts in the Middle East were also a cause of concern.
During the 1990s, there was relative peace in the United States airspace as the threat of domestic hijacking was seen as a distant memory. Globally, however, hijackings still persisted. Between 1993 and 2003, the highest number of hijackings occurred in 1993 (see table below). This number can be attributed to events in China where hijackers were trying to gain political asylum in Taiwan. Europe and the rest of East Asia were not immune either. On December 26, 1994, Air France Flight 8969 with 172 passengers and crew was hijacked after leaving Algiers. Authorities believed that the goal was to crash the plane into the Eiffel Tower. On June 21, 1995, All Nippon Airways Flight 857 was hijacked by a man claiming to be a member of the Aum Shinrikyo religious cult, demanding the release of its imprisoned leader Shoko Asahara. The incident was resolved when the police stormed the plane.
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On October 17, 1996, the first hijacking that was brought to an end while airborne was carried out by four operatives of the Austrian special law enforcement unit Cobra on a Russian Aeroflot flight from Malta to Lagos, Nigeria, aboard a Tupolev Tu-154. The operatives escorted inmates detained for deportation to their homelands and were equipped with weapons and gloves. On 12 April 1999, six ELN members hijacked a Fokker 50 of Avianca Flight 9463, flying from Bucaramanga to Bogotá. Many hostages were held for more than a year, and the last hostage was finally freed 19 months after the hijacking.
2001–present.
On September 11, 2001, four airliners were hijacked by 19 Al-Qaeda extremists: American Airlines Flight 11, United Airlines Flight 175, American Airlines Flight 77 and United Airlines Flight 93. The first two planes were deliberately crashed into the Twin Towers of the World Trade Center in New York City and the third was crashed into The Pentagon in Arlington County, Virginia. The fourth crashed in a field in Stonycreek Township near Shanksville, Pennsylvania after crew and passengers attempted to overpower the hijackers. Authorities believe that the intended target was the U.S. Capitol or the White House in Washington DC. In total, 2,996 people (2,977 if excluding the perpetrators) perished and more than 6,000 were injured in the attacks, making the hijackings the deadliest in modern history.
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Following the attacks, the U.S. government formed the Transportation Security Administration (TSA) to handle airport screening at U.S. airports. Government agencies around the world tightened their airport security, procedures and intelligence gathering. Until the September 11 attacks, there had never been an incident whereby a passenger aircraft was used as a weapon of mass destruction. The 9/11 Commission report stated that it was always assumed that a "hijacking would take the traditional form"; therefore, airline crews never had a contingency plan for a suicide-hijacking. As Patrick Smith, an airline pilot, summarizes:
Throughout the mid-2000s, hijackings still occurred but there were much fewer incidents and casualties. The number of incidents had been declining, even before the September 11 attacks. One notable incident in 2006 was the hijacking of Turkish Airlines Flight 1476, flying from Tirana to Istanbul, which was seized by a man named Hakan Ekinci. The aircraft, with 107 passengers and 6 crew, made distress calls to air traffic control and the plane was escorted by military aircraft before landing safely at Brindisi, Italy. In 2007, several incidents occurred in the Middle East and Northern Africa; hijackers in one of these incidents claimed to be affiliated with Al-Qaeda. Towards the end of the decade, AeroMexico experienced its first terror incident when Flight 576 was hijacked by a man demanding to speak with President Calderón. In 2007, a man failed to hijack a 737-200 with 103 people on board over Chad.
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Between 2010 and 2019, the Aviation Safety Network estimates there have been 15 hijackings worldwide with three fatalities. This is a considerably lower figure than in previous decades which can be attributed to greater security enhancements and awareness of September 11–style attacks. On June 29, 2012, an attempt was made to hijack Tianjin Airlines Flight GS7554 from Hotan to Ürümqi in China. More recently was the 2016 hijacking of EgyptAir Flight MS181, involving an Egyptian man who claimed to have a bomb and ordered the plane to land in Cyprus. He surrendered several hours later, after freeing the passengers and crew.
Countermeasures.
As a result of the large number of U.S.–Cuba hijackings in the late 1960s to early 1970s, international airports introduced screening technology such as metal detectors, X-ray machines and explosive detection tools. In the U.S., these rules were enforced starting from January 1973 and were eventually copied around the world. These security measures made hijacking a "higher-risk proposition" and deterred criminals in later decades. Until September 2001, the FAA set and enforced a "layered" system of defense: hijacking intelligence, passenger pre-screening, checkpoint screening and on-board security. The idea was that if one layer were later to fail, another would be able stop a hijacker from boarding a plane. However, the 9/11 Commission found that this layered approach was flawed and unsuitable to prevent the September 11 attacks. The U.S. Transportation Security Administration has since strengthened this approach, with a greater emphasis on intelligence sharing.
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On-board security.
In the history of hijackings, most incidents involved planes being forced to land at a certain destination with demands. As a result, commercial airliners adopted a "total compliance" rule which taught pilots and cabin crew to comply with the hijackers' demands. Crews advise passengers to sit quietly to increase their chances of survival. The ultimate goal is to land the plane safely and let the security forces handle the situation. The FAA suggested that the longer a hijacking persisted, the more likely it would end peacefully with the hijackers reaching their goal. Although total compliance is still relevant, the events of September 11 changed this paradigm as this technique cannot prevent a murder-suicide hijacking.
After the September 11 attacks, it became evident that each hijacking situation needs to be evaluated on a case-by-case basis. Cabin crew, now aware of the severe consequences, have a greater responsibility for maintaining control of their aircraft. Most airlines also give crew members training in self-defense tactics. Ever since the 1970s, crew are taught to be vigilant for suspicious behaviour. For example, passengers who have no carry-on luggage, or are standing next to the cockpit door with fidgety movements. There have been various incidents when crew and passengers intervened to prevent attacks: on December 22, 2001, Richard Reid attempted to ignite explosives on American Airlines Flight 63. In 2009, on Northwest Flight 253, Umar Farouk Abdulmutallab attempted to detonate explosives sewn into his underwear. In 2012, the attempted hijacking of Tianjin Airlines Flight 7554 was stopped when cabin crew placed a trolley in-front of the cockpit door and asked passengers for help.
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Cockpit security.
As early as 1964, the FAA required cockpit doors on commercial aircraft be kept locked during flight. In 2002, U.S. Congress passed the Arming Pilots Against Terrorism Act, allowing pilots at U.S. airlines to carry guns in the cockpit. Since 2003, these pilots are known as Federal Flight Deck Officers. It is estimated that one in 10 of the 125,000 commercial pilots are trained and armed. Also in 2002, aircraft manufacturers such as Airbus introduced a reinforced cockpit door which is resistant to gunfire and forced entry. Shortly afterwards, the FAA required operators of more than 6,000 aircraft to install tougher cockpit doors by April 9, 2003. Rules were also tightened to restrict cockpit access and make it easier for pilots to lock the doors. In 2015, Germanwings Flight 9525 was seized by the co-pilot and deliberately crashed, while the captain was out. The captain was unable to re-enter the cockpit, because the airline had already reinforced the cockpit door. The European Aviation Safety Agency issued a recommendation for airlines to ensure that at least two people, one pilot and a member of cabin crew, occupy the cockpit during flight. The FAA in the United States enforce a similar rule.
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Air marshal service.
Some countries operate a marshal service, which puts members of law enforcement on high-risk flights based on intelligence. Their role is to keep passengers safe, by preventing hijackings and other criminal acts committed on a plane. Federal marshals in the U.S. are required to identify themselves before boarding a plane; marshals of other countries often are not. According to the Congressional Research Service, the budget for the U.S. Federal Air Marshal Service was US$719 million in 2007. Marshals often sit as regular passengers, at the front of the plane to allow observation of the cockpit. Despite the expansion of the marshal service, they cannot be on every plane, and they rarely face a real threat on a flight. Critics have questioned the need for them.
Air traffic control.
There is no generic or set of rules for handling a hijacking situation. Air traffic controllers are expected to exercise their best judgement and expertise when dealing with the apparent consequences of an unlawful interference or hijack. Depending on the jurisdiction, the controller will inform authorities, such as the military, who will escort the hijacked plane. Controllers are expected to keep communications to a minimum and clear the runway for a possible landing.
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Legislation for downing hijacked aircraft.
Germany.
In January 2005, a federal law came into force in Germany, called the , which allows "direct action by armed force" against a hijacked aircraft to prevent a September 11–style attack. However, in February 2006 the Federal Constitutional Court struck down these provisions of the law, stating such preventive measures were unconstitutional and would essentially be state-sponsored murder, even if such an act would save many more lives on the ground. The main reason behind this decision was that the state would effectively be killing innocent hostages in order to avoid a terrorist attack. The Court also ruled that the Minister of Defense is constitutionally not entitled to act in terrorism matters, as this is the duty of the state and federal police forces. President of Germany Horst Köhler urged judicial review of the constitutionality of the "Luftsicherheitsgesetz" after he signed it into law in 2005.
India.
India published its anti-hijacking policy in August 2005. The policy came into force after approval from the Cabinet Committee on Security (CCS). The main points of the policy are:
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United States.
Prior to the September 11 attacks, countermeasures were focused on "traditional" hijackings. As such, there were no specific rules for handling suicide hijackings, where aircraft would be used as a weapon. Moreover, military response at the time consisted of multiple uncoordinated units, each with its own set of rules of engagement with no unified command structure. Soon after the attacks, however, new rules of engagement were introduced, authorizing the North American Aerospace Defense Command (NORAD), the U.S. Air Force command tasked with protecting U.S. airspace, to shoot down hijacked commercial airliners if the plane is deemed a threat to strategic targets. In 2003, the military stated that fighter pilots exercise this scenario several times a week.
Other countries.
Poland and Russia are among other countries that have had laws or directives for shooting down hijacked planes. However, in September 2008 the Polish Constitutional Court ruled that the Polish rules were unconstitutional, and voided them.
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International law.
Tokyo Convention.
The Convention on Offences and Certain Other Acts Committed on Board Aircraft, known as the Tokyo Convention, is an international treaty which entered force on December 4, 1969. , it has been ratified by 186 parties. Article 11 of the Tokyo Convention states the following:
The signatories agree that if there is unlawful takeover of an aircraft, or a threat of it on their territory, then they will take all necessary measures to regain or keep control over an aircraft. The captain can also disembark a suspected person on the territory of any country, where the aircraft lands, and that country must agree to it, as stated in Articles 8 and 12 of the convention.
Hague Convention.
The Convention for the Suppression of Unlawful Seizure of Aircraft (known as the Hague Convention) went into effect on October 14, 1971. , the convention has 185 signatories.
Montreal Convention.
The Montreal Convention is a multilateral treaty adopted by a diplomatic meeting of ICAO member states in 1999. It amended important provisions of the Warsaw Convention's regime concerning compensation for the victims of air disasters.
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Acropolis of Athens
The Acropolis of Athens (; ) is an ancient citadel located on a rocky outcrop above the city of Athens, Greece, and contains the remains of several ancient buildings of great architectural and historical significance, the most famous being the Parthenon. The word "Acropolis" is . The term acropolis is generic and there are many other acropoleis in Greece. During ancient times the Acropolis of Athens was also more properly known as Cecropia, after the legendary serpent-man Cecrops, the supposed first Athenian king.
While there is evidence that the hill was inhabited as early as the 4th millennium BC, it was Pericles (–429 BC) in the fifth century BC who coordinated the construction of the buildings whose present remains are the site's most important ones, including the Parthenon, the Propylaea, the Erechtheion and the Temple of Athena Nike. The Parthenon and the other buildings were seriously damaged during the 1687 siege by the Venetians during the Morean War when gunpowder being stored by the then Turkish rulers in the Parthenon was hit by a Venetian bombardment and exploded.
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History.
Early settlement.
The Acropolis is located on a flattish-topped rock that rises above sea level in the city of Athens, with a surface area of about . While the earliest artifacts date to the Middle Neolithic era, there have been documented habitations in Attica from the Early Neolithic period (6th millennium BC).
There can be little doubt that a Mycenaean megaron palace stood upon the hill during the late Bronze Age. Nothing of this structure survives except, probably, a single limestone column base and pieces of several sandstone steps. Soon after the palace was constructed, a Cyclopean massive circuit wall was built, 760 meters long, up to 10 meters high, and ranging from 3.5 to 6 meters thick. From the end of the Helladic IIIB (1300–1200 BC) on, this wall would serve as the main defense for the acropolis until the 5th century. The wall consisted of two parapets built with large stone blocks and cemented with an earth mortar called "emplekton" (Greek: ἔμπλεκτον). The wall uses typical Mycenaean conventions in that it followed the natural contour of the terrain and its gate, which was towards the south, was arranged obliquely, with a parapet and tower overhanging the incomers' right-hand side, thus facilitating defense. There were two lesser approaches up the hill on its north side, consisting of steep, narrow flights of steps cut in the rock. Homer is assumed to refer to this fortification when he mentions the "strong-built house of Erechtheus" ("Odyssey" 7.81). At some time before the 13th century BC, an earthquake caused a fissure near the northeastern edge of the Acropolis. This fissure extended some 35 meters to a bed of soft marl in which a well was dug. An elaborate set of stairs was built and the well served as an invaluable, protected source of drinking water during times of siege for some portion of the Mycenaean period.
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Archaic Acropolis.
Not much is known about the architectural appearance of the Acropolis until the Archaic era. During the 7th and the 6th centuries BC, the site was controlled by Kylon during the failed Kylonian revolt, and twice by Peisistratos; each of these was attempts directed at seizing political power by "coups d'état". Apart from the Hekatompedon mentioned later, Peisistratos also built an entry gate or propylaea. Nevertheless, it seems that a nine-gate wall, the Enneapylon, had been built around the acropolis hill and incorporated the biggest water spring, the Clepsydra, at the northwestern foot.
A temple to Athena Polias, the tutelary deity of the city, was erected between 570 and 550 BC. This Doric limestone building, from which many relics survive, is referred to as the Hekatompedon (Greek for "hundred–footed"), Ur-Parthenon (German for "original Parthenon" or "primitive Parthenon"), H–Architecture or Bluebeard temple, after the pedimental three-bodied man-serpent sculpture, whose beards were painted dark blue. Whether this temple replaced an older one or just a sacred precinct or altar is not known. Probably, the Hekatompedon was built where the Parthenon now stands.
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Between 529 and 520 BC yet another temple was built by the Pisistratids, the Old Temple of Athena, usually referred to as the Arkhaios Neōs (ἀρχαῖος νεώς, "ancient temple"). This temple of Athena Polias was built upon the Dörpfeld foundations, between the Erechtheion and the still-standing Parthenon. The Arkhaios Neōs was destroyed as part of the Achaemenid destruction of Athens during the Second Persian invasion of Greece during 480–479 BC; however, the temple was probably reconstructed during 454 BC, since the treasury of the Delian League was transferred in its opisthodomos. The temple may have been burnt down during 406/405 BC as Xenophon mentions that the old temple of Athena was set afire. Pausanias does not mention it in his 2nd century AD "Description of Greece".
Around 500 BC the Hekatompedon was dismantled to make place for a new grander building, the Older Parthenon (often referred to as the Pre-Parthenon or Early Parthenon). For this reason, Athenians decided to stop the construction of the Olympieion temple which was connoted with the tyrant Peisistratos and his sons, and, instead, used the Piraeus limestone destined for the Olympieion to build the Older Parthenon. To accommodate the new temple, the south part of the summit was cleared, made level by adding some 8,000 two-ton blocks of limestone, a foundation deep at some points, and the rest was filled with soil kept in place by the retaining wall. However, after the victorious Battle of Marathon in 490 BC, the plan was revised and marble was used instead. The limestone phase of the building is referred to as Pre-Parthenon I and the marble phase as Pre-Parthenon II. In 485 BC, construction stalled to save resources as Xerxes became king of Persia, and war seemed imminent.
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The Older Parthenon was still under construction when the Persians invaded and sacked the city in 480 BC. The building was burned and looted, along with the Ancient Temple and practically everything else on the rock. After the Persian crisis had subsided, the Athenians incorporated many architectural parts of the unfinished temple (unfluted column drums, triglyphs, metopes, etc.) into the newly built northern curtain wall of the Acropolis, where they served as a prominent "war memorial" and can still be seen today. The devastated site was cleared of debris. Statuary, cult objects, religious offerings, and unsalvageable architectural members were buried ceremoniously in several deeply dug pits on the hill, serving conveniently as a fill for the artificial plateau created around the Classical Parthenon. This "Persian debris" was the richest archaeological deposit excavated on the Acropolis by 1890.
The Periclean building program.
After winning at Eurymedon during 468 BC, Cimon and Themistocles ordered the reconstruction of the southern and northern walls of the Acropolis. Most of the major temples, including the Parthenon, were rebuilt by order of Pericles during the so-called Golden Age of Athens (460–430 BC). Phidias, an Athenian sculptor, and Ictinus and Callicrates, two famous architects, were responsible for the reconstruction.
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During 437 BC, Mnesicles started building the Propylaea, a monumental gate at the western end of the Acropolis with Doric columns of Pentelic marble, built partly upon the old Propylaea of Peisistratos. These colonnades were almost finished during 432 BC and had two wings, the northern one decorated with paintings by Polygnotus. About the same time, south of the Propylaea, building started on the small Ionic Temple of Athena Nike in Pentelic marble with tetrastyle porches, preserving the essentials of Greek temple design. After an interruption caused by the Peloponnesian War, the temple was finished during the time of Nicias' peace, between 421 BC and 409 BC.
Construction of the elegant temple of Erechtheion in Pentelic marble (421–406 BC) was by a complex plan which took account of the extremely uneven ground and the need to circumvent several shrines in the area. The entrance, facing east, is lined with six Ionic columns. Unusually, the temple has two porches, one on the northwest corner borne by Ionic columns, the other, to the southwest, supported by huge female figures or caryatids. The eastern part of the temple was dedicated to Athena Polias, while the western part, serving the cult of the archaic king Poseidon-Erechtheus, housed the altars of Hephaestus and Voutos, brother of Erechtheus. Little is known about the original plan of the interior, which was destroyed by fire during the first century BC and has been rebuilt several times.
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During the same period, a combination of sacred precincts including the temples of Athena Polias, Poseidon, Erechtheus, Cecrops, Herse, Pandrosos and Aglauros, with its Kore Porch (Porch of the Maidens) or Caryatids' Balcony was begun. Between the temple of Athena Nike and the Parthenon, there was the Sanctuary of Artemis Brauronia (or the Brauroneion), the goddess represented as a bear and worshipped in the deme of Brauron. According to Pausanias, a wooden statue or "xoanon" of the goddess and a statue of Artemis made by Praxiteles during the 4th century BC were both in the sanctuary.
Behind the Propylaea, Phidias' gigantic bronze statue of Athena Promachos ("Athena who fights in the front line"), built between 450 BC and 448 BC, dominated. The base was high, while the total height of the statue was . The goddess held a lance, the gilt tip of which could be seen as a reflection by crews on ships rounding Cape Sounion, and a giant shield on the left side, decorated by Mys with images of the fight between the Centaurs and the Lapiths. Other monuments that have left almost nothing visible to the present day are the Chalkotheke, the Pandroseion, Pandion's sanctuary, Athena's altar, Zeus Polieus's sanctuary and, from Roman times, the circular Temple of Roma and Augustus.
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Hellenistic and Roman Period.
During the Hellenistic and Roman periods, many of the existing buildings in the area of the Acropolis were repaired to remedy damage from age and occasionally war. Monuments to foreign kings were erected, notably those of the Attalid kings of Pergamon Attalos II (in front of the NW corner of the Parthenon), and Eumenes II, in front of the Propylaea. These were rededicated during the early Roman Empire to Augustus or Claudius (uncertain) and Agrippa, respectively. Eumenes was also responsible for constructing a stoa on the south slope, similar to that of Attalos in the agora below.
During the Julio-Claudian period, the Temple of Roma and Augustus, a small, round edifice about 23 meters from the Parthenon, was to be the last significant ancient construction on the summit of the rock. Around the same time, on the north slope, in a cave next to the one dedicated to Pan since the Classical period, a sanctuary was founded where the archons dedicated to Apollo on assuming office. During 161 AD, on the south slope, the Roman Herodes Atticus built his grand amphitheater or odeon. It was destroyed by the invading Herulians a century later but was reconstructed during the 1950s.
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During the 3rd century, under threat from a Herulian invasion, repairs were made to the Acropolis walls, and the Beulé Gate was constructed to restrict entrance in front of the Propylaea, thus returning the Acropolis to use as a fortress.
Byzantine, Latin, and Ottoman Period.
During the Byzantine period, the Parthenon was used as a church dedicated to the Virgin Mary. During the Latin Duchy of Athens, the Acropolis functioned as the city's administrative center, with the Parthenon as its cathedral, and the Propylaea as part of the ducal palace. A large tower was added, the Frankopyrgos (Frankish Tower), demolished during the 19th century.
After the Ottoman conquest of Greece, the Propylaea were used as the garrison headquarters of the Turkish army, the Parthenon was converted into a mosque and the Erechtheum was turned into the governor's private harem. The buildings of the Acropolis suffered significant damage during the 1687 siege by the Venetians in the Morean War. The Parthenon, which was being used as a gunpowder magazine, was hit by artillery and damaged severely.
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During subsequent years, the Acropolis was a site of bustling human activity with many Byzantine, Frankish, and Ottoman structures. The dominant feature during the Ottoman period was a mosque inside the Parthenon, complete with a minaret.
The Acropolis was besieged thrice during the Greek War of Independence—two sieges from the Greeks in 1821–1822 and one from the Ottomans in 1826–1827. A new bulwark named after Odysseas Androutsos was built by the Greeks between 1822 and 1825 to protect the recently rediscovered Klepsydra spring, which became the sole fresh water supply of the fortress.
Independent Greece.
After independence, most features that dated from the Byzantine, Frankish, and Ottoman periods were cleared from the site in an attempt to restore the monument to its original form, "cleansed" of all later additions. The Parthenon mosque was demolished in 1843, and the Frankish Tower in 1875. German Neoclassicist architect Leo von Klenze was responsible for the restoration of the Acropolis in the 19th century, according to German historian Wolf Seidl, as described in his book "Bavarians in Greece".
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Some antiquities from the Acropolis were exhibited in the old Acropolis Museum, which was built in the second half of the 19th century.
At the beginning of the Axis occupation of Greece in 1941, German soldiers raised the Nazi German War Flag over the Acropolis. It would be taken down by Manolis Glezos and Apostolos Santas in one of the first acts of resistance. In 1944 Greek Prime Minister Georgios Papandreou arrived on the Acropolis to celebrate liberation from the Nazis.
Archaeological remains.
The entrance to the Acropolis was a monumental gateway termed the Propylaea. To the south of the entrance is the tiny Temple of Athena Nike. At the centre of the Acropolis is the Parthenon or Temple of Athena Parthenos (Athena the Virgin). East of the entrance and north of the Parthenon is the temple known as the Erechtheum. South of the platform that forms the top of the Acropolis there are also the remains of the ancient, though often remodelled, Theatre of Dionysus. A few hundred metres away, there is the now partially reconstructed Odeon of Herodes Atticus.
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Many of the valuable ancient artifacts are situated in the Acropolis Museum, which resides on the southern slope of the same rock, 280 metres from the Parthenon.
Site plan.
Site plan of the Acropolis at Athens showing the major archaeological remains.
The Acropolis Restoration Project.
The Acropolis Restoration Project began in 1975 to reverse the decay of centuries of attrition, pollution, destruction from military actions, and misguided past restorations. The project included the collection and identification of all stone fragments, even small ones, from the Acropolis and its slopes, and the attempt was made to restore as much as possible using reassembled original material (anastylosis), with new marble from Mount Pentelicus used sparingly. All restoration was made using titanium dowels and is designed to be completely reversible, in case future experts decide to change things. A combination of cutting-edge modern technology and extensive research and reinvention of ancient techniques were used.
The Parthenon colonnades, largely destroyed by Venetian bombardment during the 17th century, were restored, with many wrongly assembled columns now properly placed. The roof and floor of the Propylaea were partly restored, with sections of the roof made of new marble and decorated with blue and gold inserts, as in the original. Restoration of the Temple of Athena Nike was completed in 2010.
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A total of 2,675 tons of architectural members were restored, with 686 stones reassembled from fragments of the originals, 905 patched with new marble, and 186 parts made entirely of new marble. A total of 530 cubic meters of new Pentelic marble were used.
In 2021, the addition of new reinforced concrete paths to the site to improve accessibility caused controversy among archaeologists.
Cultural significance.
Every four years, the Athenians had a festival called the Great Panathenaea that rivaled the Olympic Games in popularity. During the festival, a procession (believed to be depicted on the Parthenon frieze) traveled through the city via the Panathenaic Way and culminated on the Acropolis. There, a new robe of woven wool ("peplos") was placed on either the statue of Athena Polias in the Erechtheum (during the annual Lesser Panathenaea) or the statue of Athena Parthenos in the Parthenon (during the Great Panathenaea, held every four years).
Within the later tradition of Western civilization and Classical revival, the Acropolis, from at least the mid-18th century on, has often been invoked as a critical symbol of the Greek legacy and of the glories of Classical Greece.
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Most of the artifacts from the temple are housed today in the Acropolis Museum at the foot of the ancient rock.
Geology.
The Acropolis is a klippe consisting of two lithostratigraphic units: the Athens schist and the overlying Acropolis limestone. The Athens schist is a soft reddish rock dating from the late Cretaceous period. The original sediments were deposited in a river delta approximately 72 million years ago. The Acropolis limestone dates from the late Jurassic period, predating the underlying Athens schist by about 30 million years. The Acropolis limestone was thrust over the Athens schist by compressional tectonic forces, forming a nappe or overthrust sheet. Erosion of the limestone nappe led to the eventual detachment of the Acropolis, forming the present-day feature. Where the Athens schist and the limestone meet there are springs and karstic caves.
Many of the hills in the Athens region were formed by the erosion of the same nappe as the Acropolis. These include the hills of Lykabettos, Areopagus, and Mouseion.
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The marble used for the buildings of the Acropolis was sourced from the quarries of Mount Pentelicus, a mountain to the northeast of the city.
Geological instability.
The limestone that the Acropolis is built upon is unstable because of the erosion and tectonic shifts that the region is prone to. This instability may cause rock slides that cause damage to the historic site. Various measures have been implemented to protect the site, including retaining walls, drainage systems, and rock bolts. These measures work to counter the natural processes that threaten the historic site.
References.
Notes
Bibliography
External links.
Videos
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Adam Weishaupt
Johann Adam Weishaupt (; 6 February 1748 – 18 November 1830) was a German philosopher, professor of civil law and later canon law, and founder of the Illuminati.
Early life.
Adam Weishaupt was born on 6 February 1748 in Ingolstadt in the Electorate of Bavaria. Weishaupt's father Johann Georg Weishaupt (1717–1753) died when Adam was five years old. After his father's death he came under the tutelage of his godfather Johann Adam von Ickstatt who, like his father, was a professor of law at the University of Ingolstadt. Ickstatt was a proponent of the philosophy of Christian Wolff and of the Enlightenment, and he influenced the young Weishaupt with his rationalism. Weishaupt began his formal education at age seven at a Jesuit school. He later enrolled at the University of Ingolstadt and graduated in 1768 at age 20 with a doctorate of law. In 1772 he became a professor of law after conversion to Protestantism. The following year he married Afra Sausenhofer of Eichstätt.
After Pope Clement XIV's suppression of the Society of Jesus in 1773, Weishaupt became a professor of canon law, a position that was held exclusively by the Jesuits until that time. In 1775 Weishaupt was introduced to the empirical philosophy of Johann Georg Heinrich Feder of the University of Göttingen. Both Feder and Weishaupt would later become opponents of Kantian idealism.
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Foundation of the Illuminati.
On 1 May 1776 Johann Adam Weishaupt founded the "Illuminati" in the Electorate of Bavaria. Initially, Illumination was designated for a group of outstanding and enlightened individuals in society. Indeed, the word was adapted from a Latin root, "Iluminatus," which directly translates to "enlightened." He also adopted the name of "Brother Spartacus" within the order. Even encyclopedia references vary on the goal of the order, such as "Catholic Encyclopedia" (1910) saying the Order was not egalitarian or democratic internally, but sought to promote the doctrines of equality and freedom throughout society; while others such as "Collier's" have said the aim was to combat religion and foster rationalism in its place. The Illuminati was formed with the vision of liberating humans from religious bondage and undermining corrupted governments.
The actual character of the society was an elaborate network of spies and counter-spies. Each isolated cell of initiates reported to a superior, whom they did not know: a party structure that was effectively adopted by some later groups.
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Weishaupt was initiated into the Masonic lodge "Theodor zum guten Rath", at Munich in 1777. His project of "illumination, enlightening the understanding by the sun of reason, which will dispel the clouds of superstition and of prejudice" was an unwelcome reform. He used Freemasonry to recruit for his own quasi-masonic society, with the goal of "perfecting human nature" through re-education to achieve a communal state with nature, freed of government and organized religion. Presenting their own system as pure masonry, Weishaupt and Adolph Freiherr Knigge, who organized his ritual structure, greatly expanded the secret organization.
Contrary to Immanuel Kant's that Enlightenment (and Weishaupt's Order was in some respects an expression of the Enlightenment Movement) was the passage by a man out of his 'self-imposed immaturity' through daring to 'make use of his own reason, without the guidance of another,' Weishaupt's Order of Illuminati prescribed in great detail everything which the members had obediently to read and think so that Dr. Wolfgang Riedel has commented that this approach to illumination or enlightenment constituted a degradation and twisting of the Kantian principle of Enlightenment. Riedel writes:
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Weishaupt's radical rationalism and vocabulary were not likely to succeed. Writings that were intercepted in 1784 were interpreted as seditious, and the Society was banned by the government of Karl Theodor, Elector of Bavaria, in 1784. Weishaupt lost his position at the University of Ingolstadt and fled Bavaria.
Activities in exile.
He received the assistance of Duke Ernest II of Saxe-Gotha-Altenburg (1745–1804), and lived in Gotha writing a series of works on illuminism, including "A Complete History of the Persecutions of the Illuminati in Bavaria" (1785), "A Picture of Illuminism" (1786), "An Apology for the Illuminati" (1786), and "An Improved System of Illuminism" (1787). Adam Weishaupt died in Gotha on 18 November 1830. He was survived by his second wife, Anna Maria (née Sausenhofer), and his children Nanette, Charlotte, Ernst, Karl, Eduard, and Alfred. His body was buried next to that of his son Wilhelm, who preceded him in death (in 1802), at Friedhof II der Sophiengemeinde Berlin, a Protestant cemetery.
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After Weishaupt's Order of Illuminati was banned and its members dispersed, it left behind no enduring traces of influence, not even on its own erstwhile members, who went on to develop in quite different directions.
Assessment of character and intentions.
Weishaupt's character and intentions have been variously assessed. Some took a negative view, such as Augustin Barruel, who despite writing that Weishaupt's goals were that "Equality and Liberty, together with the most absolute independence, are to be the substitutes for all rights and all property" saw this as more dangerous than beneficial, and John Robison, who regarded Weishaupt as a 'human devil' and saw his mission as one of malevolent destructiveness. Others took a more positive view, including Thomas Jefferson, who wrote in a letter to James Madison that "Barruel’s own parts of the book are perfectly the ravings of a Bedlamite and considered Weishaupt to be an "enthusiastic Philanthropist" who believed in the indefinite perfectibility of man, and believed that the intention of Jesus Christ was simply to "reinstate natural religion, and by diffusing the light of his morality, to teach us to govern ourselves".
In his defence, Weishaupt wrote a "Kurze Rechtfertigung meiner Absichten" (A Brief Justification of my Intentions) in 1787. Author Tony Page comments:
Works.
Works relating to the Illuminati.
Source
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Acorn Electron
The Acorn Electron (nicknamed the Elk inside Acorn and beyond) was introduced as a lower-cost alternative to the BBC Micro educational/home computer, also developed by Acorn Computers, to provide many of the features of that more expensive machine at a price more competitive with that of the ZX Spectrum. It has 32 kilobytes of RAM, and its ROM includes BBC BASIC II together with the operating system. Announced in 1982 for a possible release the same year, it was eventually introduced on 25 August 1983 priced at £199.
The Electron is able to save and load programs onto audio cassette via a cable, originally supplied with the computer, connecting it to any standard tape recorder with the appropriate sockets. It is capable of bitmapped graphics, and can use either a contemporary television set, a colour (RGB) monitor or a monochrome monitor as its display. Several expansions were made available to provide many of the capabilities omitted from the BBC Micro. Acorn introduced a general-purpose expansion unit, the Plus 1, offering analogue joystick and parallel ports, together with cartridge slots into which ROM cartridges, providing software, or other kinds of hardware expansions, such as disc interfaces, could be inserted. Acorn also produced a dedicated disc expansion, the Plus 3, featuring a disc controller and 3.5-inch floppy drive.
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For a short period, the Electron was reportedly the best selling micro in the United Kingdom, with an estimated 200,000 to 250,000 machines sold over its entire commercial lifespan. With production effectively discontinued by Acorn as early as 1985, and with the machine offered in bundles with games and expansions, later being substantially discounted by retailers, a revival in demand for the Electron supported a market for software and expansions without Acorn's involvement. Its market for games also helped to sustain the continued viability of games production for the BBC Micro.
History.
After Acorn Computers released the BBC Micro, executives believed that the company needed a less expensive computer for the mass market. In May 1982, when asked about the recently announced Sinclair ZX Spectrum's potential to hurt sales of the BBC Micro, priced at £125 for the 16K model compared to around twice that price for the 16K BBC Model A, Acorn co-founder Hermann Hauser responded that in the third quarter of that year Acorn would release a new £120–150 computer which "will probably be called the Electron", a form of "miniaturised BBC Micro", having 32 KB of RAM and 32 KB of ROM, with "higher resolution graphics than those offered by the Spectrum". Acorn co-founder Chris Curry also emphasised the Electron's role as being "designed to compete with the Spectrum... to get the starting price very low, but not preclude expansion in the long term."
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Development.
In order to reduce component costs, and to prevent cloning, the company reduced the number of chips in the Electron from the 102 on the BBC Micro's motherboard to "something like 12 to 14 chips" with most functionality on a single 2,400-gate Uncommitted Logic Array (ULA).
The operating system ROM locations 0xFC00-0xFFFF contain the details of some members of the Electron's design team, these differing somewhat from those listed in the corresponding message in the BBC Model B ROM:
Additionally, the last bytes of both the BASIC ROM and the Plus 3 interface's ADFS v1.0 ROM include the word "Roger", thought to be a reference to Roger Wilson. The case was designed by industrial designer Allen Boothroyd of Cambridge Product Design.
Release.
Reports during the second half of 1982 indicated a potential December release, with Curry providing qualified confirmation of such plans, together with an accurate depiction of the machine's form and capabilities, noting that the "massive ULA" would be the "dominant factor" in any pre-Christmas release. As the end of the year approached, the machine itself was pictured in press reports. With the ULA not ready for "main production", however, the launch of the Electron was to be delayed until the spring.
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By June 1983, with the planned March release having passed, the launch of the Electron had been rescheduled for the "Acorn User" Exhibition in August 1983, and the machine was indeed launched at the event. The company expected to ship the Electron before Christmas, and sell 100,000 by February 1984. The price at launch£199remained unchanged from that stated in an announcement earlier in the year, with the machine's nickname within Acornthe "Elk"also being reported publicly for perhaps the first time.
Reviews were generally favourable, starting with positive impressions based on the physical design of the computer, with one reviewer noting, "The Electron is beautifully designed and builtquite a shock compared to the BBC. Its designer case will look great on the coffee table." Praise was also forthcoming for the Electron's keyboard which was regarded as being better than most of its low-cost peers, with only the VIC-20 being comparable. In one review, the keyboard was even regarded as better than the one in the BBC Micro. The provision of rapid BASIC keyword entry though the combination of the key with various letter keys was also welcomed as a helpful aid to prevent typing errors by "most users", while "touch typists" were still able to type out the keywords in full.
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Reviewers also welcomed the machine's excellent graphics compared to its rivals, noting that "the graphics are much more flexible and the maximum resolution is many times that of the Spectrum's". The provision of screen modes supporting 80 columns of readable text and graphics resolutions of 640×256 was described as "unrivalled by every machine up to the BBC Model B itself", although the absence of a teletext mode was considered regrettable. Although valued for its low memory usage characteristics in the BBC Micro, one reviewer considered the absence of a "software simulation of a teletext screen" to be a "lazy omission" even if it would have to be "awfully slow and take up piles of memory".
While its speed was acceptable compared to its immediate competition, the Electron was, however, rather slower than the BBC Micro with one review noting that games designed for the BBC Micro ran "at less than half the speed, with very significant effects on their appeal". The reduced performance can be attributed to the use of a 4-bit wide memory system instead of the 8-bit wide memory system of the BBC Micro to reduce cost. Due to needing two accesses to the memory instead of one to fetch each byte, along with contention with the video hardware also needing access, reading or writing RAM was much slower than on the BBC Micro. Reviewers were also disappointed by the single-channel sound, noting that "BBC-style music" and its "imitations of various musical instruments" would not be possible, the latter due to the inability of the sound system to vary the amplitude of sounds.
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Despite some uncertainty about Acorn's target demographic for the Electron, some noted the potential for the machine in education given its robustness, but also given its price, noting that the high price of BBC Model B machines seemed "rarely justified by their actual practical applications in schools". The introduction of the Electron was seen as potentially leading to competition between Acorn's different models within the schools market rather than creating a broader audience for them, although the potential for more computers in schools, giving more "hands-on" experience for students, was welcomed. Nevertheless, reviewers anticipated that the Electron would sell well at the lower end of the market, with projected sales of 100,000 units by Christmas 1983, helped by the Electron's software compatibility with the BBC Micro and the already established reputation of its predecessor. With parents potentially being convinced of the Electron's educational value, some reviewers foresaw a conflict between parents and "discerning children", the latter merely wanting to play games and preferring models with sound and graphics capabilities more appropriate for gaming.
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Although Acorn had based its expansion into the United States on the BBC Micro, the company did have plans to introduce the Electron at a later time, with Chris Curry having indicated "a very heavy push overseas" involving both the BBC Micro and Electron. A model for the US market was described in an official book, "The Acorn Guide to the Electron", but this model was never produced. The Electron was distributed in various other markets and was reviewed by home computing publications in countries such as Norway, West Germany, and New Zealand.
Production and volume delivery.
Production difficulties at Astec in Malaysia delayed the machine's introduction, forcing Acorn to look to other manufacturers such as AB Electronics in Wales and Wongs in Hong Kong (an original equipment manufacturer making over 30 million circuit boards a year, along with power supplies and plastic housings, for companies such as IBM, Xerox, Atari, and Apple, including units made for Acorn for the BBC Micro). By October 1983, Acorn had received orders for more than 150,000 units, but had production targets of only 25,000 a month before Christmas, meaning that the existing backlog would take more than six months to fulfil. Demand for the Electron was high but only two of WH Smith's London branches had inventory. Ultimately, manufacturing in Malaysia ceased with the anticipated but unspecified number of units having been produced, this having been originally reported as 100,000 units. Acorn's marketing manager, Tom Hohenberg, admitted in early 1984 that "a lot of the trouble stemmed from the ULA" in getting production to the desired levels, but that such difficulties had been resolved, although Acorn faced an order backlog of almost a quarter of a million units.
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As the company increased production during 1984, however, the British home computer market greatly weakened. Hohenberg later noted that after the 1983 Christmas season, Electron deliveries had increased to meet a demand that was no longer there, with the market having "completely dried up". Acorn's Christmas 1984 sales were greatly below expectations and by March 1985 the company had reduced the Electron's price to £129. With the company's unsuccessful expansion into the United States abandoned, Acorn's financial situation had deteriorated sufficiently to prompt Olivetti to rescue the company by taking a 49.30% ownership stake. Renewed efforts were made to sell the machine, bundling it with Acorn's own expansions and software, such as one package adding the Plus 1 expansion, joysticks and a ROM cartridge game to the base machine for a total price of £219. Acorn committed to supporting the machine "until the end of 1986", continuing to supply it (as the Merlin M2105) to British Telecom as part of the Healthnet communications system, with small-scale manufacturing continuing while existing stocks were being run down.
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By autumn, retailers appeared eager to discount the computer, with prices in stores as low as £100, reportedly less than the distributor prices of the summer months. As the Christmas season approached, Dixons Retail acquired the remaining Electron inventory to sell, bundled with a cassette recorder and software, at a retail price of £99.95. This deal, from the perspective of a year later, apparently played a significant part in helping to reduce Acorn's unsold inventory from a value of £18 million to around £7.9 million, and in combination with "streamlining corporate activities and reducing overheads", had helped to reduce Acorn's losses from over £20 million to less than £3 million.
The deal effectively brought to an end Acorn's interest in the Electron and the lower-cost end of the home computing market, but empowered third-party suppliers whose "inventiveness and initiative" was noted as being in contrast with Acorn's lack of interest in the product and the "false promises" made to its users. However, Acorn subsequently released the Master Compact a model in the Master series of microcomputers with fewer BBC Micro-style ports and a similar expansion connector to that used by the Electron with the home audience specifically in mind. Indeed, prior to its release, the Master Compact had been perceived as the successor to the Electron. Superficial similarities between the Compact and Acorn Communicator, together with technical similarities between the Electron (particularly when expanded in the form of the Merlin M2105) and the Communicator, may also have driven rumours of an updated Electron model. A more substantial emphasis on the "home, music and hobby sectors" came with the appointment of a dedicated marketing manager in 1989 following the launch of the BBC A3000 in the Acorn Archimedes range.
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Hardware.
Much of the core functionality of the BBC Micro the video and memory controller, cassette input/output, timers and sound generation was replicated using a single customised ULA chip designed by Acorn in conjunction with Ferranti, albeit with only one sound channel instead of three (and one noise channel), and without the character-based Teletext Mode 7.
The keyboard includes a form of quick keyword input, similar to that used on the Sinclair ZX Spectrum, through use of the key in combination with other keys labelled with BASIC keywords. However, unlike the Spectrum, this method of rapid keyword entry is optional, and keywords can be entered manually if preferred.
The edge connector on the rear of the Electron exposes all address and data bus lines from the CPU, including the upper eight bits of the address bus, in contrast to the limited selection available via the BBC Micro's expansion ports, with the One Megahertz Bus as the principal mechanism for general purpose expansion on the BBC Micro only providing the lower eight bits of the address bus. In addition, various control signals provided by the CPU and ULA are exposed via the Electron's expansion connector.
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The ULA mediates access to 32 KB of addressable RAM using four 4164 DRAMs (64 K×1 bit), sharing the RAM between the CPU and the video signal generation (or screen refresh) performed by the ULA itself. Two accesses have to be made to the RAM to get each byte (albeit with a single RAS), delivering a maximum transfer rate to or from RAM of one byte per 2 MHz cycle. In generating the video signal, the ULA is able to take advantage of this 2 MHz bandwidth when producing the picture for the high-bandwidth screen modes. Due to signalling constraints, the CPU can only access RAM at 1 MHz, even when it is not competing with the video system.
When the ULA is consuming all of the RAM bandwidth during the active portion of a display line, the CPU is unable to access the RAM. (The Electron uses the Synertek variant of the 6502 processor as that allowed the clock to be stopped for this 40 microsecond period.) In other modes the CPU and video accesses are interleaved with each accessor acquiring bytes at 1 MHz.
In contrast, the BBC Micro employs one or two sets of eight 16-kilobit devices, with the RAM running at twice the speed (4 MHz) of the CPU (2 MHz), allowing the video system (screen refresh) and CPU memory accesses to be interleaved, with each accessor able to transfer bytes at 2 MHz. The RAM access limitations imposed by the Electron's ULA therefore reduce the effective CPU speed by as much as a factor of four relative to the BBC Micro in the more demanding display modes, and as much as a factor of two otherwise. Byte transfers from ROM occur at 2 MHz, however.
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For issue 1–4 motherboards, the ULA had an issue similar to those experienced by other socketed CPUs. Over time, the thermal heating and cooling could cause the ULA to rise slightly out of its socket just enough to cause the machine to hang or freeze and for other issues to occur preventing the start-up of the machine, in some cases causing the initial beep or tone to sound continuously. This was despite a metal cover and a locking-bar mechanism designed to prevent this from occurring. Pushing down on the metal cover to reseat the ULA was normally sufficient to rectify these issues. Issue 5 and 6 boards utilized a different ULA type, this being known as the Aberdeen ULA (as opposed to the earlier Ferranti ULA) which was mounted on a board that was directly soldered to the main board, with the chip being covered by epoxy resin "insulating material". This arrangement dispensed with the 68-pin socket, and this new type of ULA was expected to be "less prone to failure". This type of ULA was also used on the German release of the Electron mainboard which is designated by the marking "GERMAN ELECTRON Issue 1" on the mainboard rather than just "ELECTRON" as for the UK model.
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Technical specifications.
The hardware specification according to official documentation, combined with more technical documentation and analysis is as follows:
The composite video output provides a greyscale image on the standard machine, but an internal modification allows a colour image to be produced, albeit with a degradation in picture quality. Acorn ostensibly intended the composite output to be a high-quality output for monochrome monitors, with the RGB output being the preferred high-quality output for colour images.
Merlin M2105.
An unusual variant of the Electron was sold by British Telecom Business Systems as the BT Merlin M2105 Communications Terminal, being previewed by British Telecom at the Communications '84 show. This consisted of a rebadged Electron plus a large expansion unit containing 32 KB of battery-backed RAM (making up 64 KB of RAM in total), up to 64 KB of ROM resident in four sockets (making up to 96 KB of ROM in total), a Centronics printer port, an RS423 serial port, a modem, and the speech generator previously offered for the BBC Micro. The ROM firmware provided dial-up communications facilities, text editing and text messaging functions. The complete product included a monitor and dot-matrix printer.
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Initially trialled in a six-month pilot at 50 florists, with the intention of rolling out to all 2,500 members of the UK network, these were used by the Interflora florists network in the UK for over a decade. Used mostly for sending messages, despite providing support for other applications, limited availability of the product led Interflora to look for alternatives after five years, although users appeared to be happy with the product as it was.
This generic product combination of the Electron and accompanying expansion was apparently known as the Chain during development, itself having a different board layout, with British Telecom having intended the M2105 to be a product supporting access to an online service known as Healthnet. This service aimed to improve and speed up communications within hospitals so that patients could be treated and discharged more quickly, and to facilitate transfers of information to doctors and health workers outside hospitals, with communications taking place over conventional telephone lines. The service was to be introduced in the Hammersmith and Fulham district health authority, with installation starting at Charing Cross Hospital. The Electron was said to be particularly suitable for deployment in this application in that it had a "large expansion bus", ostensibly making the machine amenable to the necessary adaptations required for the role, together with its "price, and the fact it has a real keyboard". As a Healthnet terminal, the M2105 was intended to support the exchange of forms, letters and memos.
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The adoption of an Acorn product in this role was perhaps also unusual in that much of BT's Merlin range of this era had been supplied by ICL, notably the M2226 small business computer and M3300 "communicating word processor". Nevertheless, the M2105 offered interoperability with other BT products such as the QWERTYphone which was able to receive messages from the M2105 and the Merlin Tonto.
The hardware specifications of the M2105, observed from manufactured units, include the 6502 CPU (SY6502 or R6502), ULA and 32 KB of dynamic RAM fitted in the Electron main unit, plus 32 KB of static RAM, two 6522 VIA devices for interfacing, AM2910PC modem, SCN2681A UART, and TMS5220 plus TMS6100 for speech synthesis. The speech synthesis was used for the "voice response" function which answered incoming voice calls by playing a synthesised message to the caller. The components chosen and the capabilities provided (excluding speech synthesis) are broadly similar to those featured by the Acorn Communicator which was another product of Acorn's custom systems division.
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The product documentation indicates a specification with 48 KB of RAM plus 16 KB of "non volatile CMOS RAM" and 96 KB of ROM, although this particular composition of RAM is apparently contradicted by the RAM devices present on surviving M2105 machines. However, the earlier Chain variant of the board does appear to provide only 16 KB of static RAM using two HM6264LP-15 chips, also providing an extra 16 KB of dynamic RAM using eight MK4516-15 chips, suggesting that the product evolved during development.
Recreations and emulators.
Several emulators of the machine exist:
Electron software is predominantly archived in the UEF file format.
There are also two publicly documented FPGA based recreations of the Acorn Electron hardware: ElectronFPGA for the Papilio Duo hardware and the Acorn-Electron core for the FPGA Arcade "Replay" board. In addition, an implementation of the ULA for the Lattice ICE40 series has been made available.
Software.
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Languages.
A significant selling point for the Electron was its built-in BBC BASIC interpreter, providing a degree of familiarity from the BBC Micro along with a level of compatibility with the earlier machine. However, as had been the case with the BBC Micro, support for other languages was quickly forthcoming, facilitated by the common heritage of the two systems.
In addition to the early releases, Forth and Lisp, Acornsoft released the Pascal subset, S-Pascal, on cassette and followed up with an ISO Pascal implementation on ROM cartridge, the latter providing two 16 KB ROMs containing a program editor and a Pascal compiler producing intermediate code that required Pascal run-time routines to be loaded. As a more minimal implementation, S-Pascal made use of the machine's built-in BASIC program editing facilities and provided a compiler generating assembly language that would then be assembled, generating machine code for direct execution. ISO Pascal had Oxford Pascal as a direct competitor offering a range of features differentiating it from Acornsoft's product, notably a compiler that could produce a stand-alone "relocatable 6502 machine-code file". Acornsoft later released the ISO Pascal Stand Alone Generator product for the BBC Micro and Master series, permitting the generation of executable programs embedding "sections of the interpreter" required by each program, with such executables being subject to various licensing restrictions.
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Acornsoft Forth, aiming for compliance with the Forth-79 standard, was regarded as "an excellent implementation of the language". It saw competition from Skywave Software's Multi-Forth 83 which was delivered on a ROM chip, supported the Forth-83 standard, and provided a multitasking environment. Future availability of Multi-Forth 83 on ROM cartridge was advertised.
With the launch of the Plus 1, Acornsoft Lisp was also made available on cartridge. This Lisp implementation provided only the "bare essentials" of a Lisp system that "a small micro such as the Electron" could hope to be able to support. However, with the interpreter and initialised workspace being loaded from cassette into RAM in the earlier release, one stated advantage of the ROM version was the availability of more memory for use by programs, with the immediacy of a Lisp system provided as a language ROM being an implicit benefit.
Acornsoft provided two products offering different degrees of support for the Logo programming language. Turtle Graphics was a cassette-based product, available alongside Forth, Lisp and S-Pascal amongst the first titles released for the Electron, featuring a subset of Logo focused on the interactive aspects of the language. Acornsoft Logo was provided on ROM cartridge and offered a vocabulary of over 200 commands as part of a more comprehensive implementation of the language, exposing its list processing foundations. Turtle Graphics was substantially cheaper than Logo: by 1987, the former had been reportedly discounted to under £3 whereas the latter cost "less than £30". Unlike other Acornsoft language products, however, Logo was supplied with "two thick manuals".
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Applications.
Acornsoft made a number of applications available for the Electron. In early 1985, the "View" word processor and "ViewSheet" spreadsheet applications, familiar from the BBC Micro, were released on ROM cartridge for use with the Electron expanded with a Plus 1, priced at £49.50 each. By running directly from ROM, these applications were able to dedicate all of the machine's available RAM to their documents, and using general filing system mechanisms, documents could be loaded from and saved to cassette or disc, although disc users could also use commands that took advantage of that faster, random-access medium. Cassette-based operation was still regarded as "perfectly feasible" since the software itself did not need to be loaded, with loading and saving operations in View achieving about 800 words per minute and in ViewSheet achieving around 200 cells per minute.
When using View in Mode 6, providing a 40-column, 25-line display occupying 8 KB of memory, around 20 KB of RAM was available to cassette-based systems or to disc-based systems using products such as the Cumana Floppy Disc System that also maintained PAGE at &E00, this corresponding to about 10 or 11 A4 pages of text. In Mode 3, providing an 80-column, 25-line display occupying 16 KB, around 6 or 7 A4 pages of text could be retained in memory. Acorn's Plus 3 disc system reduced this workspace by a further 4 KB. However, documents could be broken up into sections to be processed individually by View. Operation in the 80-column Mode 0 and Mode 3 was reported as being "sometimes slow" due to the Electron's hardware architecture, but View supported horizontal scrolling across documents, permitting the use of a 40-column mode to edit wider documents.
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ViewSheet could also operate in different display modes, with spreadsheets of approximately 1600 cells being editable in Mode 6 and around 800 cells in Mode 3. A windowing system was provided that permitted ten different views of a spreadsheet to be displayed on screen at once, and recalculation operations were reported to be "around ten seconds for quite a large model". Reviewers considered the View and ViewSheet applications to be "professional" and to "compare well with similar software sold for much more expensive machines" such as the IBM PC, with WordStar being noted as a broadly similar package to View. Compatibility with the same programs on the BBC Micro made a complete Electron-based system an attractive, low-cost, entry-level word processing and spreadsheet system. However, View's printing support was criticised as inadequate without the use of a companion printer driver program.
Acornsoft did not release its "ViewStore" database program specifically for the Electron, but the software was reported as being compatible, albeit with function key combinations different to those documented for the BBC Micro. However, Acornsoft did release a product, "Database", on 3.5-inch diskette for use with the Electron upgraded with the Plus 3 expansion. The product provided a suite of programs for the creation, maintenance and analysis of structured data files, visualising records using a card index user interface metaphor, and supporting sorting and searching operations on the stored data.
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Slogger, an established provider of expansions, also produced productivity applications such as "Starword", a word processor, and "Starstore", a database. Starword provided separate command and editing modes familiar from Acornsoft's View, also supporting 132-column documents and horizontal scrolling for the editing of such wider documents. Along with other operations familiar from View, such as search and replace functions, block-based editing, and control over text justification, it had built-in support for customising documents for output using a mail merge function. Available on ROM for fitting to a ROM expansion such as Slogger's Rombox or inside a separately purchased ROM cartridge, and reportedly developed specifically for the Electron, Starword was considered "comprehensive and powerful".
Starstore, also available on ROM, provided a database management suite primarily aimed at users of cassette storage, with databases being entirely resident in RAM. It supported database definition, data editing, searching, sorting and printing activities. Various features complemented Starword, such as mail merge integration. "Starstore II" followed on as an alternative to, as opposed to a direct successor of, the earlier Starstore product by requiring a disc-based system and permitting databases to be as large as the amount of free space on any given disc. Its user interface was improved over the earlier product, offering pop-up menus and cursor-based navigation.
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Computer Concepts' "Wordwise Plus", developed from the company's earlier Wordwise product for the BBC Micro and launched in early 1985, was made available for use with the Electron expanded with the E2P-6502 second processor cartridge. The original Wordwise product was incompatible with the Electron due to its use of Mode 7 (the BBC Micro's 40-column Teletext display mode), and being supplied on a ROM chip, it could also not be readily added to the Electron without appropriate expansions. Available from Permanent Memory Systems, producers of the E2P-6502 cartridge, the Electron version of the software was the Hi-Wordwise Plus variant, supplied on disc instead of ROM, and designed to run on the second processor and to use the expanded memory provided in that environment. The program used the Electron's 40-column Mode 6 display.
Expansion manufacturers Advanced Computer Products and Slogger both made solutions available based on products from Advanced Memory Systems. ACP released a bundle of the "AMX Mouse" and "AMX Art" software for use with its Advanced Plus 5 expansion, also requiring a DFS-compatible disc system. Slogger produced a version of the desktop publishing package "Stop Press" for the Electron, requiring a DFS-compatible disc system, two spare ROM sockets, a mouse, and a suitable user port expansion, with Slogger producing its own user port expansion cartridge. Competing with these products but requiring only a disc system, AVP's "Pixel Perfect" offered a rudimentary desktop publishing solution, utilising the computer's high-resolution Mode 0 display.
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Games.
Of the twelve software titles announced by Acornsoft for the Electron at the machine's launch, six were games titles: "Snapper", "Monsters" (a clone of Space Panic), "Meteors" (a clone of Asteroids), "Starship Command", "Chess", and the combined title "Draughts and Reversi". When the Plus 1 expansion was launched in 1984, three of these titles"Hopper", "Snapper" and "Starship Command"were among the six ROM cartridge titles available at launch, together with the adventure "Countdown to Doom". Acornsoft would continue to release games including those based on existing arcade games such as "Arcadians" (based on Galaxian) and "Hopper" (based on Frogger), as well as original titles such as "Free Fall" and "Elite".
Micro Power, already an established BBC Micro games publisher, also entered the Electron market at a relatively early stage, offering ten initial titles either converted from the BBC Micro, in the case of "Escape from Moonbase Alpha" and "Killer Gorilla", or "completely re-written", in the case of "Moonraider" (due to differences in the screen handling between the machines). Superior Software, also a significant publisher for the BBC Micro, routinely released games for both machines, notably a licensed version of Atari's Tempest in 1985, but also successful original titles such as the "Repton" series of games, "Citadel", "Thrust" and "Galaforce". Superior's role in games publishing for the Acorn machines expanded in 1986 when the company acquired the right to use the Acornsoft brand, leading to the co-branding of games and compilations released by the company and the re-release of existing Acornsoft titles with this branding, Elite among them. The company would subsequently release another "masterpiece" with bundled novellathe 1988 game "Exile"as well as numerous conversions and compilations.
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By 1988, the "big three" full-price games publishers for the Acorn 8-bit market were identified as Superior Software, Audiogenic (ASL) and Tynesoft, with Top Ten and Alternative Software being the significant budget publishers, and other "strong contenders" being Godax, Mandarin and Bug Byte, this assessment made from the perspective of an established games author evaluating trustworthy publishers for aspiring authors. Commercial considerations motivated authors to make their games available for the Electron due to its importance in sales terms, representing "around half of the Acorn market", with it being regarded as "almost compulsory for any mainstream game" to have an Electron version "unless your game is a state-of-the-art masterpiece", with "Revs", "Cholo" and "Sentinel" cited as such BBC Micro exclusives. Although the Electron imposed additional technical constraints on authors accustomed to the BBC Micro, some authors were able to use this to their creative advantage. For instance, of "Frak!" it was noted that the "Electron version is more popular, and considered better than the BBC version because it has a screen designer included".
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Although not as well supported by the biggest software publishers as rivals like the Commodore 64 and Sinclair ZX Spectrum, a good range of games were available for the Electron including popular multi-format games such as "Chuckie Egg". There were also many popular games officially converted to the Electron from arcade machines (including "Crystal Castles", "Tempest", "Commando", "Paperboy", and "Yie Ar Kung-Fu") and other home computer systems (including "Impossible Mission", "Jet Set Willy", "The Way of the Exploding Fist", "Tetris", "The Last Ninja", "Barbarian", "Ballistix", "Predator", "Hostages" and "SimCity").
Despite Acorn themselves effectively shelving the Electron in 1985, games continued to be developed and released by professional software houses until the early 1990s. There were around 1,400 games released for the Acorn Electron, several thousand extra public domain titles were released on disc through Public Domain libraries. Notable enterprises which produced discs of such software are BBC PD, EUG (Electron User Group) and HeadFirst PD.
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Development considerations and techniques.
Like the BBC Micro, the Electron is constrained by limited memory resources. Of the 32 KB RAM, 3½ KB is allocated to the OS at startup and at least 10 KB is taken up by the display buffer in contiguous display modes.
Although programs running on the BBC Micro can use the machine's 6522 chip to trigger interrupts at certain points in the update of each display frame, using these events to change the palette and potentially switching all colours to black, thus blanking regions of the screen and hiding non-graphical data that had been stored in screen memory, the Electron lacks such hardware capabilities as standard. However, it was found to be possible to take advantage of the characteristics of interrupts that were provided, permitting palette changes after the top 100 lines of each display frame, thus facilitating the blanking of either the top 100 or bottom 156 lines of the display. Many games took advantage of this, gaining storage by leaving non-graphical data in the disabled area.
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Other games would simply load non-graphical data into the display and leave it visible as regions of apparently randomly coloured pixels. One notable example is Superior Software's Citadel.
Although page flipping is a hardware possibility, the limited memory forced most applications to do all their drawing directly to the visible screen, often resulting in graphical flicker or visible redraw. A notable exception is Players' "Joe Blade" series.
A number of unusual techniques were employed by some developers to work around apparent limitations of the hardware.
Firetrack: smooth vertical scrolling.
Although programs can alter the position of the screen in memory, the non-linear format of the display means that vertical scrolling can only be done in blocks of 8 pixels without further work.
"Firetrack", released on a compilation by Superior Software, exploits a division in the way the Electron handles its display of the seven available graphics modes, two are configured so that the final two of every ten scanlines are blank and are not based on the contents of RAM. If 16 scanlines of continuous graphical data are written to a character-block-aligned portion of the screen then they will appear as a continuous block in most modes but in the two non-continuous modes they will be displayed as two blocks of eight scanlines, separated in the middle by two blank scanlines.
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In order to keep track of its position within the display, the Electron maintains an internal display address counter. The same counter is used in both the continuous and non-continuous graphics modes and switching modes mid-frame does not cause any adjustment to the counter.
"Firetrack" switches from a non-continuous to a continuous graphics mode part way down the display. By using the palette to mask the top area of the display and taking care about when it changes mode it can shift the continuous graphics at the bottom of the display down in two pixel increments because the internal display counter is not incremented on blank scanlines during non-continuous graphics modes.
Exile: sampled speech.
"Exile" turns the Electron's one channel output into a digital speaker for PCM output.
The speaker can be programmatically switched on or off at any time but is permanently attached to a hardware counter so is normally only able to output a square wave. But if set to a frequency outside the human audible range then the ear can't perceive the square wave, only the difference between the speaker being switched on and off. This gives the effect of a simple toggle speaker similar to that seen in the 48 KB Sinclair ZX Spectrum. "Exile" uses this to output 1-bit audio samples.
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Frak! and Zalaga: polyphonic music.
As part of their copy protection, illegal copies of Aardvark Software's "Frak!" and "Zalaga" would cause a pseudo-polyphonic rendition of Trumpet Hornpipe, the Captain Pugwash theme tune, to play endlessly rather than loading the game properly (Pugwash being a pirate). On the Electron version of Frak!, the tune was the main theme from "Benny Hill" (Boots Randolph's "Yakety Sax"). The polyphony was achieved via fast note-switching to achieve the necessary chords.
Hardware expansions.
Since the Electron provides only a selection of video output ports, a cassette port and the expansion connector, a range of additional expansions were produced to offer ports and connections to various peripherals. The first expansions were largely joystick and printer interfaces or sideways ROM boards. For instance, First Byte Computers developed an interface and software which allowed a "switched" joystick to be used with the majority of software titles. This interface became very popular and was sold by W.H. Smiths, Boots, Comet and hundreds of independent computer dealers, selling as many as 23,000 units over a two-year period, helped by a bundling agreement with Dixons.
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Acorn's own expansion strategy was led by the Plus 1 which offered a combination of ports and cartridge connectors, followed by the Plus 3 disc drive unit, but by early 1986 the more general range of expansions had broadened to include floppy drive and RS423 interfaces, Teletext adapters, and other fundamental enhancements to the base machine.
Multi-function expansions.
Since the Electron's expansion connector was the basis of practically all external hardware expansions for the machine, unless an expansion propagated this connector to others, as was done by the Acorn Plus 3, the capabilities of any given expansion would limit the capabilities of the expanded machine. Thus, expansions offering a single function, such as joystick ports or a printer port, would need to be disconnected if other capabilities were needed, and then reconnected later. Consequently, multi-function expansions offering a combination of different capabilities offered a significant degree of convenience as well as avoiding wear on the expansion connector.
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Alongside announcements of Acorn's then-unreleased Plus 1, Solidisk previewed a General Purpose Interface for the Electron in early 1984 offering a Centronics printer port, switched joystick port, user port, sideways ROM sockets, and mini-cartridge sockets supported by the 6522 versatile interface adapter (VIA) chip. The Plus 1 itself was released in mid-1984, introducing the influential cartridge format for expansions ultimately used by several other companies.
Acorn Plus 1.
The Acorn Plus 1 added two ROM cartridge slots, an analogue interface (supporting four channels) and a Centronics parallel port, priced at £59.90. The analogue interface was normally used for joysticks, although trackball and graphics tablet devices were available, and the parallel interface was typically used to connect a printer. Game ROM cartridges would boot automatically. Languages in paged ROM cartridges would take precedence over BASIC. (The slot at the front of the interface took priority if both were populated.)
Access to ROM occurs at 2 MHz until RAM access is required, so theoretically programs released on ROM can run up to twice as fast as those released on tape or disc. Despite this, all of the games released on ROM were packaged as ROM filing system cartridges, from which the micro would load programs into main memory in exactly the same way as if it were loading from tape. This meant that programs did not need to be modified for their new memory location and could be written in BASIC but gave no execution speed benefits. Six ROM cartridge titles were announced for the launch of the Plus 1: three arcade games, one adventure game, one educational title, and the "Lisp" language implementation, the latter being a genuine language ROM that "takes the place of the BASIC ROM" and is instantly available when switching on.
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The cartridge slots provide additional control lines (compared to the lines available via the edge connector on the rear of the Electron) to ease implementation of ROM cartridges. Acorn described the hardware extension possibilities in promotional literature, giving an RS423 cartridge as an example of this capability of the Plus 1.
Additional peripheral cartridges were produced by companies such as Advanced Computer Products (and subsequently PRES) whose Advanced ROM Adaptor (ARA) and Advanced Sideways RAM (ASR) products provided sideways ROM and RAM capabilities, allowing ROM- or EPROM-based software to be accessed to provide languages, utilities and applications. ROM or EPROM devices containing the software could be physically inserted into empty ZIF sockets, or the software would be loaded from ROM image files (typically provided on disk) into RAM devices fitted in such sockets. Such RAM could potentially be powered by a battery and thus be able to retain its contents when the computer itself was powered off. Both such arrangements exposed the software in the same sideways memory region.
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Such cartridge support enabled the Electron to provide the same functionality as that offered by the expansion ROM slots under the keyboard and on the bottom-left of the BBC Micro B keyboard. However, the need to use cartridge sockets for other peripherals encouraged PRES to develop the Advanced Plus 6 (AP6): an internal RAM and ROM board for the Plus 1 providing six sockets that could be freely used for ROM, EPROM and RAM devices. Installation of the AP6 unit required some modifications to the Plus 1, undertaken either by the user or by PRES, and the product could also be enhanced with the Advanced Plus 7 offering battery-backed RAM support for two 16 KB banks.
The addition of the Plus 1 added a number of new *FX or OSBYTE calls that allowed the OS to read values from the analogue interface and write to the parallel interface.
The Plus 1 needed memory page &D for its workspace, and the unit added some processing overhead when enabled, both of these things causing issues with the loading and running of software, particularly cassette-based games. To disable the Plus 1, after pressing BREAK, the following commands could be issued:
*FX163,128,1
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?&212=&D6
?&213=&F1
?&2AC=0
An official application note described a similar set of commands to "remove the Plus One completely from the address map disabling the Centronics and A/D ports (additionally disabling the RS423 cartridge if fitted)".
Further developments.
After Acorn's change of focus away from the Electron, and with a shortage of Plus 1 units available to purchase, Advanced Computer Products secured the rights to manufacture the unit under licence from Acorn, obtaining the injection moulds and tooling, thus restarting production in 1987 after Acorn's own production of the unit had ceased in November 1985. The Advanced Plus 2 (AP2) ROM was later sold by PRES as a replacement ROM for the Plus 1, of whose 8 KB utility ROM only 3 KB had been used, thus providing an opportunity for a more comprehensive ROM to be developed. The AP2 added ROM management commands familiar from the BBC Master series, support for various sideways RAM products from PRES, disc formatting and verification utilities for different ADFS versions, a command to disable the Plus 1 entirely, and improvements that made tape loading more reliable in "high memory" screen modes.
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Slogger Rombox Plus.
Following on from Slogger's earlier Rombox product an expansion similar in profile to the Plus 1 but offering eight ROM sockets and propagating the expansion connector to other units the Rombox Plus was positioned more directly as a competitor to the Plus 1 in that it offered two cartridge slots and a Centronics print port alongside four ROM sockets. Priced at £49.95, the unit was mostly compatible with cartridges designed for the Plus 1 although one reviewer reported physical issues with some expansion cartridges, suggesting some manufacturing inconsistencies given other users' more positive experiences, but indicated that it was still "worth considering as an alternative to the Plus 1". One review reported that the Cumana Electron Filing System cartridge had an edge connector that would not physically fit inside the slot in the Rombox Plus unit; this along with a perceived lack of robustness of the case being their only major reservations about the product. The product's support for utilising 8 KB RAM devices as a printer buffer, with buffer management provided by the built-in EPROM, was noted as a particular advantage over the Plus 1.
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Slogger Remote Expansion and Plus 2.
In early 1989, Slogger announced its "remote expansion" (RX) system for the Electron, providing a separate case with power supply to house expansions and disc drives, able to support the weight of a monitor or television. Intended for the RX system, the Plus 2 offered two ROM cartridge slots compatible with the Plus 1, three ROM sockets, and RS423 and user port capabilities. One application of the user port was to connect a mouse, utilised by Slogger's version of the Stop Press desktop publishing package by Advanced Memory Systems.
Software Bargains Plus 1.
In mid-1989, Software Bargains announced an expansion providing different levels of Plus 1 functionality, offered as a bare printed circuit board without casing and in three different variants: the basic model offered one cartridge port and was bundled with View and Viewsheet cartridges for £29.95; an extended model offered one cartridge port and a printer port with the two bundled cartridges for £36.95; the full model offered two cartridge ports, printer port and the bundled cartridges for £39.95. Various board upgrade options were also offered between the variants, with the product being described mainly as a vehicle to expose the bundled software packages to as many as 150,000 owners of the estimated 200,000 Electrons in the UK who "have not yet been able to acquire or use View or Viewsheet". The lack of casing was considered the most significant disadvantage, with the absence of the analogue port deemed less critical due to a general lack of support for joysticks in many games.
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Communications and networking.
To support connectivity, Acorn announced a Plus 2 network interface with availability scheduled for early 1985, together with a RS423 cartridge for the Plus 1. Neither of these products were delivered as announced.
Acorn Plus 2.
The Acorn Plus 2 interface was due to provide Econet capability. This interface did not make it to market. However, an Econet interface was produced by Barson Computers in Australia and possibly other individuals and businesses.
Acorn Plus 4.
The Acorn Plus 4 interface was due to provide a modem communications capability.
Andyk RS423 cartridge.
Andyk announced an RS423 cartridge for the Plus 1 providing a serial port, alongside other products, in late 1985. It was priced at £34.99.
Pace Tellstar/Nightingale.
Originally reported in mid-1985 as a collaboration between Acorn and Pace Micro Technology, but launched in early 1986, Pace offered a communications product consisting of a RS423 cartridge, bundled with a Nightingale modem and Tellstar communications software, retailing at around £161 but discounted to £145. The substantially reduced price of the Electron itself created an opportunity that Pace was "exploiting nicely" with its telecommunications bundle, described by one commentator as "a marvellous opportunity to get a cheap Prestel set in addition to your normal computer".
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Jafa Systems RS423 cartridge.
Jafa Systems announced an RS423 cartridge in late 1989 to "fill a two year gap in the market", offering a serial connector compatible with the BBC Micro together with an on-board socket for 8 KB or 16 KB EPROM devices or for 32 KB RAM, the latter being configured to present two sideways RAM banks to the system. Write protect functionality was supported to prevent certain ROM software from attempting to overwrite itself if stored in RAM. The cartridge board itself was priced at around £30, with a case costing £5 extra, and an optional 32 KB RAM adding another £20. Support for the E00 ADFS offered by PRES for that company's AP3 disc system was indicated as an application for the sideways RAM.
Slogger Plus 2 RS423 interface.
Slogger provided an RS423 interface as an option for its own Plus 2 expansion, announced in early 1989.
Disc interfaces.
The first disc interface to be announced for the Electron was Pace's Le Box in 1984, offering a single-sided 100 KB floppy drive controlled by the 8271 controller and accessed using the Amcom Disc Filing System, with pricing at £299 plus VAT including the drive or around £199 without. The unit also provided eight sideways ROM sockets and was intended to sit under the Electron itself. The unit was connected via cabling to the expansion edge connector and included its own power supply, and other drives including switchable 40/80 track drives offering up to 400 KB capacity were dealer-supplied options. Although the product was meant to be on sale at the Acorn User Show in August 1984, and had been advertised, it was "discontinued" in early 1985 before getting to market, with a Pace representative indicating that prohibitive pricing of the 8271 chips (each at "over £80 at times") had left the company considering a re-launch of the product should the pricing situation become more favourable.
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Following on from Acorn's Plus 3 interface, Cumana, Solidisk, Advanced Computer Products and Slogger all offered disc interfaces for the Electron. Unlike disc systems on the BBC Micro and the Acorn Plus 3, many of the systems released for the Electron did not claim RAM workspace (and raise the PAGE variable affecting applications above the default of &E00), making it easier to use cassette-based software transferred to disc and to run larger programs from disc.
Low-cost alternatives to disc systems, briefly made fashionable by press coverage of the Sinclair Microdrive, were reportedly under development by expansion suppliers such as Solidisk, and finished products such as the Phloopy looped tape system were offered for the Electron. Reliability issues were described with the Phloopy, and the product was apparently short-lived.
Acorn Plus 3.
Launched in late 1984 for a price of £229, the Acorn Plus 3 was a hardware module that connected independently of the Plus 1 and provided a "self contained disc interface and 3.5 inch single sided disc drive" offering over 300 KB of storage per disc using the newly introduced Advanced Disc Filing System (ADFS). The Plus 3 was also reportedly produced with a double-sided drive fitted.
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An expansion connector for a second 3.5- or 5.25-inch drive was also provided by the unit, with such drives needing to provide a Shugart-compatible connector and their own power supply. The original Electron edge connector was repeated on the back of the Plus 3, allowing the Plus 1 or other compatible expansion to be connected in conjunction with the Plus 3.
The double-density drive of the Plus 3 was driven using a WD1770 drive controller by the ADFS. (The Plus 3 had been rumoured to offer Acorn's DFS and to feature an 8272 double-density disk controller before its launch.) Because the WD1770 is capable of single-density mode and uses the same IBM360-derived floppy disc format as the Intel 8271 found in the BBC Micro, it was also possible to use the Disc Filing System with an alternate ROM, such as the ACP 1770 DFS.
The Plus 3 reset PAGE to &1D00, reducing the amount of free RAM available to the user. The ADFS system could be temporarily disabled (and PAGE reset to &E00) via the command. Later products such as the PRES E00 ADFS remedied the memory demands of the ADFS, along with other issues suffered by the software as delivered with the Plus 3. If using the Plus 3 in screen modes 0–3, the pseudo-variable would be thrown off, as the interrupts were disabled during disk access in these modes. The screen would also blank during disc accesses.
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Disks had to be manually mounted and dismounted using the / commands, or using the ++ key combination. Disks could also be booted from via the standard + key-combination, if the !BOOT file was present on the disk. This behaviour was the same as on the BBC Micro.
The Plus 3 included an uprated square black power supply unit with mains cord, manufactured by STC, designed and manufactured in England to and , that was designed to power the Plus 3, in addition to the Electron and the Plus 1 interface as well. This replaced the original cream-coloured "wall wart" style power supply, designed to and manufactured in Hong Kong.
Repair note: If the internal power-supply connector, used to power the existing internal 3.5-inch drive is damaged, and requires replacement, then the original AMP 800-930 4-pin connector, which was already in short supply during the original production run, may be replaced with a Molex 5264 50-37-5043 "Mini-SPOX" connector as an alternative.
Advanced Plus 3.
Designed and produced by Baildon Electronics and sold by PRES, the Advanced Plus 3 (AP3) was a Plus 1 cartridge interface using the WD1770 controller, supplied with Acorn's ADFS and a single-sided 3½-inch disc drive for £99 plus VAT, offering equivalent functionality to the Acorn Plus 3. Announced in late 1987, the product was made possible by an agreement between ACP and Acorn to license the ADFS software. As with many disc interfaces for the Electron, since the interface provided a connector for the drive, this made it possible to connect a 5¼" floppy disc drive (more common amongst BBC Micro owners) or the more typical 3½-inch drive.
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PRES later released a version of ADFS with support for PAGE at &E00, this being achieved by using RAM provided by the Advanced Battery Backed RAM (ABR) cartridge. This version also fixed two notable bugs in Acorn's ADFS, eliminating unreliability when accessing the first tracks on a disc which had previously necessitated the writing of a file (ZYSYSHELP) as a workaround, and switching off the text cursor during disc compaction which had previously caused disc corruption (since the disc data would be processed using screen memory during this operation, and the cursor would modify that data when blinking). The ROM image was supplied on disc for £17.19, whereas a bundle of the ROM and ABR cartridge was £50.95.
In 1989, the Advanced Plus 3 Mark 2 was launched, offering a double-sided drive in place of the single-sided drive previously offered. This meant that the storage capacity of each disc was increased from the 320 KB of the original Plus 3 to 640 KB (this being supported by ADFS on the Master Compact).
Cumana Floppy Disc System.
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Early in 1985, Cumana released a cartridge-based interface providing support for double-density storage, a real-time clock and calendar for timestamping of files, and a spare ROM socket for user-fitted sideways ROMs. The filing system used was Cumana's own QFS, supporting 89 files per disc, PAGE at &E00, a non-hierarchical catalogue, ten-character filenames, with a format not directly compatible with either of Acorn's DFS or ADFS. The interface itself cost £149.95 when originally announced, but settled at around £115.95 including VAT, also being offered in a promotional bundle with a 5¼-inch drive for £224.15 including VAT. Later pricing put the interface at £74.95 including VAT.
Solidisk EFS.
In mid-1985, Solidisk released a cartridge-based interface with support for single and double density storage and providing Acorn DFS and ADFS compatibility, 16 KB of on-board sideways RAM, and a connector for a Winchester hard drive. The cartridge itself cost £59, with a bundle including a double-sided, double-density, 3½-inch drive costing £200. A 20 MB hard drive was offered at a price of £805.
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Advanced Plus 4.
Announced in early 1986, the Advanced Plus 4 (AP4) from Advanced Computer Products was a cartridge-based interface employing the WD1770 controller and featuring ACP's 1770 DFS product, providing compatibility with Acorn's DFS from the BBC Micro and thereby supporting seven-character filenames and up to 31 files per disc. However, 8 KB of on-board static RAM was used as workspace for the filing system, keeping PAGE at &E00. An extra ROM socket was provided for a user-fitted sideways ROM, and being a 1770-based interface, it was reported that Acorn's ADFS could be used instead, although since it was not aware of the additional RAM, PAGE would be raised to &1D00 as it would be when using Acorn's Plus 3. The interface was priced at £69.55 plus VAT.
Slogger Electron Disc System and Pegasus 400.
Slogger, an established producer of expansions and a reseller of other disc systems, introduced the Electron Disc System in early 1987, priced at £74.95, featuring the Cumana Floppy Disc System interface, which was combined with an Acorn-compatible DFS, SEDFS, having the capability of reading 40-track discs on 80-track drives plus support for Slogger's tape-to-disc conversion products, and reported as offering "virtual 100 per cent 8271 emulation" for compatibility with traditional DFS software. The SEDFS ROM was also available separately for existing Cumana interface owners, priced at £24.95.
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The SEDFS was later bundled with Slogger's own cartridge-based interface and a 40/80-track switchable drive offering up to 400 KB storage per disc, with the bundle taking the Pegasus 400 name, introduced as part of a sales tour towards the end of 1987. This package of interface and drive cost £130. The precise DFS variant used by the Pegasus 400 system kept PAGE at &E00 and introduced "typeahead" support, permitting keystroke buffering during disc activity on systems with the Turbo-Driver or Master RAM Board fitted and enabled.
Slogger/Elektuur Turbo boards.
Announced in early 1986, the Slogger Turbo-Driver was a professionally fitted upgrade priced at £42. The board itself plugged into the CPU and BASIC ROM sockets on the main circuit board of the Electron, which merely involved removing socketed components on very early Electron models, but required desoldering work and therefore benefited from a fitting service for later units. The performance benefit of fitting the board was to make some programs, particularly those running in the high bandwidth modes (0 to 3), run up to three times faster.
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The direct origins of the Slogger product appear to be a board designed by Andyk Limited, announced as the Fast Electron Board in late 1985 with a price of £29.99, whereas the Elektuur modification was described in an article in Dutch Electronics magazine Elektuur and intended for users to perform at home.
The Slogger and Elektuur Turbo boards were born out of a hack initially devised at Acorn. By shadowing the lowest 8 KB of RAM with a static RAM chip outside of reach of the ULA, the CPU could always access it at 2 MHz. The tradeoff was that the screen could not be located in that 8 KB. In practice the operating system ROMs always put the screen into the top 20 KB and as a result this probably only broke compatibility with around 2% of software. Speeding up the low portion of memory is particularly useful on 6502 derived machines because that processor has a faster addressing for the first 256 bytes and so it is common for software to put any variables involved in time-critical sections of program into that region.
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The cost of the 64 Kbit SRAM chip would have been more than that of doubling the four 64 Kbit DRAM chips to give 8-bit RAM access, fixing both the modest memory and poor performance issues of the Electron.
Slogger Master RAM Board.
Introduced at around the start of 1987 and priced at £64.95 fitted or £54.95 as a kit, the Master RAM Board offered the familiar turbo mode from the Slogger Turbo-Driver alongside a shadow mode providing 32 KB of static shadow RAM in addition to the existing 32 KB, thus giving 64 KB in total. So-called "legally written software", this being software using the operating system calls and not writing directly to the screen, could function without significant modification, making substantially more memory available for BASIC, View, Viewsheet, language ROMs and many other applications. By providing extra storage this modification also allowed some games and applications intended for the BBC Micro to function on the Electron despite the lack of a native Mode 7.
Applications could not directly address video memory in shadow mode without modification, so it was incompatible with most games, although there is no inherent reason why a game could not be written to function in shadow mode. A switch mounted through the case switched between normal, turbo and shadow modes.
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Towards the end of the Electron's commercial lifetime, the Turbo-Driver and Master RAM Boards were offered already fitted to new Electrons in an attempt to increase sales. For a time, Jafa Systems manufactured their own equivalent of the Master RAM Board in order to support their own product range.
Mode 7 display expansions.
One of the features of the BBC Micro that was absent in the Electron was the Teletext-style "Mode 7" display. The omission of this display mode was remarkable because it had a very low memory requirement (just 1000 bytes) and many BBC programs used it to maximise available memory for program code and data while also providing a colourful 40-column textual display with simple low-resolution graphical decorations.
Such display capabilities, desirable in their own right on low-memory computers, were also desirable for delivering content through low-bandwidth communications channels such as that from Teletext and Viewdata services. However, access to such services can be considered to be a separate capability, and the BBC Micro needed to be upgraded to complement its display capability with the Teletext or Prestel adapters to receive such over-the-air or online content.
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Jafa Systems provided a number of solutions to remedy the absence of a Teletext display capability. Morley Electronics instead chose to offer an expansion combining the display and reception capabilities.
Sir Computers.
In late 1984, Sir Computers announced a Mode 7 adapter unit that plugged into the Electron's expansion connector. Unfortunately, Sir Computers ceased trading before the product was brought to market.
Jafa Systems.
Released in 1987 at a price of £89, the Mode 7 Mark 1 Display Unit was a separate unit "about the size, shape and colour of the Plus One or a Slogger ROMbox" that connected to the Electron's expansion connector and featured a Motorola 6845 display controller and Mullard SAA5050 character generator to replicate the main elements of the BBC Micro's Teletext display solution. This only used 1 KB of memory for the display, with the expansion listening to display memory write accesses and buffering the data in its own memory. A ROM was included to extend the operating system to allow activation of Mode 7 as a genuine screen mode and to provide extra commands and to support keyboard shortcuts used on the BBC Micro to emit Teletext control sequences. To support the output of both the Mode 7 display and the existing video output, a lead connected the Electron's RGB output to the expansion, with the expansion providing only RF (television) output.
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Conscious of the relatively high price of the Mark 1 unit, John Wike of Jafa devised and, at the end of 1988, introduced a software-based "Mode 7 Simulator", priced at £25, supplied on a ROM cartridge that rendered the Mode 7 display in a low-resolution, 8-colour graphics mode. Although cheap and effective in enabling use of some software that only used official operating system routines for text output, this solution proved very slow because the Electron had to be placed into the high-bandwidth Mode 2 display to be able to show eight colours at once. In doing so, the CPU spent a lot of time drawing representations of Mode 7 characters and graphics that in a hardware solution would be achieved without any demand on the CPU. It also used up 20 KB of RAM for the graphics display rather than the 1000 bytes of a hardware Mode 7.
A conceptually similar predecessor to the software-based simulator was published by Electron User in early 1987, offering a monochrome Mode 4 simulation of the Teletext display, using the lower 25 character lines of the screen to show the Teletext output, reserving several lines at the top of the screen for a representation of Mode 7 used to prepare the eventual visual output. However, the program did not support direct access to Mode 7 memory locations. The author noted that a Mode 2 version would have been possible but would have required a redesigned character set and "too much memory".
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A further refinement of the hardware solution was introduced in 1989 with the Mode 7 Mark 2 Display Unit, which retained the SAA5050 character generator but omitted the 6845 display controller, and was fitted internally in the Electron itself instead of being housed in an external unit, although some kind of ROM expansion unit was needed to hold the driver/utilities ROM. It used software to ensure that the SAA5050 was fed with the correct character data. A software ROM would put the machine into a two-colour, 40-column graphics mode (thus providing one byte per character), and as the ULA read display data from memory in the usual fashion, the SAA5050 would listen to the data it was reading and produce a Mode 7 interpretation of the same information, this being achieved by fitting a board on top of the ULA connecting to its pins. When necessary the hardware would switch between the conventional Electron graphics output and the Mode 7 output being produced by the add-on, feeding it to the Electron's built-in video output sockets via the red, green and blue lines on the motherboard.
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The disadvantage to this system is that while the SAA5050 would expect to be repeatedly fed the same 40 bytes of data for every display scanline of each character row, the ULA would read a different set of 40 bytes for every display scanline in order to produce a full graphics display. A software ROM worked around this by duplicating the data intended for a Mode 7 display in memory. Although this produced a Mode 7 that had less of an impact upon CPU performance than a software solution, gave the same visual quality as the BBC Micro, and supported direct access to Mode 7 screen addresses as well as accesses via operating system routines, it still used 10 KB of memory for the display and reduced the amount of readily-usable application memory (as indicated by HIMEM) by another 6 KB.
However, with users increasingly able to rely on expansions such as the Slogger Master RAM board to provide more memory, and with this combination of expansions acknowledged throughout the user manual, the emphasis of the Mode 7 Simulator and Mark 2 Display Unit was arguably to deliver the actual display capabilities for those applications that needed them, instead of using Mode 7 as a way of economising with regard to memory usage, and to do so at a reasonable price. In this latter regard, the Mark 2 model was available as a kit costing £25 or as an assembled product (requiring some soldering) costing £49, with a fitting service available for £10.
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The Jafa interfaces did not provide a Teletext or Viewdata reception capability, but the Mark 2 was explicitly stated to work in conjunction with the Morley Electronics Teletext Adapter. Meanwhile, the manual for the Mark 2 noted that the product would provide the functionality of a Viewdata terminal if combined with Jafa's RS423 cartridge.
Morley Electronics.
Morley Electronics produced a Teletext Adaptor expansion for the BBC Micro and the Electron. Since the BBC Micro has the Mode 7 display capability, the model aimed at the BBC Micro merely provided the content reception capability needed to receive and decode Teletext signals, connecting to the user port and power supply. However, the Electron models provided both display and reception capabilities, doing so by routing either the RGB or UHF signals (depending on the model) through the unit in order to introduce the Mode 7 output produced by the unit, also connecting via a cartridge. The Teletext display capabilities in the Electron models exceeded those of the BBC Micro, with one reviewer noting that the enhanced capabilities permitted "black text on a coloured background, something I've always wanted to do on my Beeb". The UHF model of the Electron adapter also supported overlaying of Teletext onto video and framing of video.
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Second Processor expansions.
Acorn did demonstrate a prototype "Tube" interface for the Electron alongside the Plus 3 interface at the Compec exhibition in November 1984, although this was never brought to market directly by Acorn.
Advanced Plus 5.
Despite Acorn's withdrawal from the Electron peripheral market, Baildon Electronics developed the Advanced Plus 5 (AP5) expansion, featuring Tube, 1 MHz bus and user port interfaces, which plugged into a Plus 1 cartridge socket. This provided a sufficient level of compatibility that both the 6502 and Z80 second processor products from Acorn were shown to work, providing a Tube implementation that was "as faithful as you can get", with it also being noted that the Electron being available for as little as £50 at that point in its commercial lifespan was a "very cheap way of getting a CP/M machine". Some differences in the memory map of the Electron meant that BBC Micro software would need modifications to work on the Electron with AP5. The price of the unit in late 1986 was £66.70.
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The additional facilities of the AP5 alongside the Tube interface permitted various expansions for the BBC Micro to be made available for the Electron. These included the Hybrid Music 5000 and the AMX Mouse.
PMS Electron Second Processor.
In 1986, Permanent Memory Systems (PMS) announced a second processor product for the Electron, the PMS-E2P, as a self-contained cartridge for use with the Plus 1 containing a second 2 MHz 6502A processor plus 64 KB of RAM, priced at £89. This was based on a product originally developed by John Wike of Jafa Systems. Available as a kit or in assembled form, it could even be adapted to connect directly to the Electron's expansion connector, thus avoiding the need to even have a Plus 1 expansion, although this would require the user to find other solutions for attaching peripherals. The implementation of the interface between the Electron and second processor was said to adhere closely to Acorn's recommendations, noting that any hardware or software compatibility issues were likely to be the fault of other vendors not similarly adhering to Acorn's guidelines. PMS supplied Acorn's Hi-BASIC with the E2P, permitting the use of as much as 44 KB of the second processor's RAM with BASIC programs. The company also made a version of Computer Concepts' Wordwise Plus available for the E2P, priced at £39.95.
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Sound system expansions.
Despite the Electron having only limited sound generation capabilities, few expansions were offered to overcome the machine's limitations.
Millsgrade Voxbox.
Advertised in late 1985, the Voxbox by Millsgrade Limited was an expansion connecting to the Electron's expansion connector that provided allophone-based speech synthesis, with driver software provided on cassette. The supplied software supported the definition of spoken words built up from the allophones these allophones or sounds being stored in the expansion's own ROM and for catalogues of words to be created and saved. A program was supplied that extended BASIC to allow the use of the synthesiser in user programs. The expansion used the General Instrument SP0256A-AL2 speech synthesis chip.
Sound Expansion cartridge.
Originally announced in 1987 by Project Expansions to be priced at around £40, the Sound Expansion cartridge could be fitted in a Plus 1 (or compatible) slot and provide sound output equivalent to that of the BBC Micro, with Superior Software's Speech bundled as a "limited offer". A product of the same name and with similar functionality was subsequently sold by Complex Software for around £55, employing its own adjustable speaker in the cartridge unit. Superior Software had announced a version of Speech for the unexpanded Acorn Electron in 1986, but this was never released.
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Hybrid Music 5000.
Hybrid Technology's Music 5000 was adapted and released by PRES for use with the 1 MHz bus of the Advanced Plus 5 expansion, with the Music 5000 itself priced at £113.85. The only functional differences between the Electron adaptation and the original BBC Micro unit involved the use of Mode 6 for the display and the reduced performance of the Electron imposing some limitations on processing in programs written for the system, although this was not thought to prevent most programs for the system from working on the Electron version.
Legacy.
Although the Electron presented challenges to developers in terms of the amount of memory available to programs and, particularly for those writing or porting games to the machine, a reduction in hardware features useful for controlling or presenting content on the screen, developers often discovered creative workarounds to deliver commercially successful products, making the business of writing conversions a viable one for some developers.
Several features that would later be associated with the BBC Master and Archimedes first appeared as features of Electron expansion units, including ROM cartridge slots and the Advanced Disc Filing System, a hierarchical improvement to the BBC's original Disc Filing System. Having been envisaged as the basis of a portable computer with "a very strong emphasis on communications" during its development, supporting both modem and Econet interfaces, the BT Merlin M2105 product subsequently combined the Electron with communications functionality, and the Acorn Communicator developed such concepts further, introducing networking support.
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The availability of the Electron at discounted prices from 1985 onwards led to increased demand for third-party software and expansions for the machine. While it may not have been as popular as the Spectrum, Commodore 64 or Amstrad CPC, it did sell in sufficient numbers to ensure that new software titles from established producers were being produced right up until the early 1990s, with mainstream publications dedicated to the machine having effectively supported it for five years beyond the point at which Acorn's own support had ceased. One reviewer concluded that even at this point in 1990, "Electron owners wishing to upgrade their machine will find themselves better served now than at any time in the machine’s history."
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A Fire Upon the Deep
A Fire Upon the Deep is a 1992 science fiction novel by American writer Vernor Vinge. It is a space opera involving superhuman intelligences, aliens, variable physics, space battles, love, betrayal, genocide, and a communication medium resembling Usenet. "A Fire Upon the Deep" won the Hugo Award in 1993, sharing it with "Doomsday Book" by Connie Willis.
Besides the normal print book editions, the novel was also included on a CD-ROM sold by ClariNet Communications along with the other nominees for the 1993 Hugo awards. The CD-ROM edition included numerous annotations by Vinge on his thoughts and intentions about different parts of the book, and was later released as a standalone e-book. It has a loose prequel, "A Deepness in the Sky", from 1999, and a direct sequel, "The Children of the Sky", from 2012.
Setting.
The novel is set in various locations in the Milky Way. The galaxy is divided into four concentric volumes called the "Zones of Thought"; it is not clear to the novel's characters whether this is a natural phenomenon or an artificially produced one, but it seems to roughly correspond with galactic-scale stellar density and a Beyond region is mentioned in the Sculptor Galaxy as well. The Zones reflect fundamental differences in basic physical laws, and one of the main consequences is their effect on intelligence, both biological and artificial. Artificial intelligence and automation is most directly affected, in that advanced hardware and software from the Beyond or the Transcend will work less and less well as a ship "descends" towards the Unthinking Depths. But even biological intelligence is affected to a lesser degree. The four zones are spoken of in terms of "low" to "high" as follows:
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One of the characters in the book, Ravna, uses this analogy to explain the relation between the zones:
Plot.
An expedition from Straumli Realm, a young human civilization in the high Beyond, investigates a newly discovered five-billion-year-old data archive in the low Transcend that offers the possibility of unimaginable riches. The expedition's facility, High Lab, is gradually and secretly compromised by an initially dormant superintelligence within the archive later known as the Blight. However, shortly before the Blight's final "flowering", two self-aware entities created similarly to the Blight plot to aid the humans before the Blight can gain its full powers.
Finally recognizing the danger, the researchers at High Lab attempt to flee in two ships, one carrying the adults and the second carrying the children in "coldsleep boxes". The Blight discovers that the first ship lists a data storage device in its cargo manifest; assuming it contains information that could harm it, the Blight destroys the ship. The second ship escapes.
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The ship lands on a distant planet with a medieval-level civilization of dog-like creatures, dubbed "Tines", who live in packs as group minds. Upon landing, however, the two surviving adults, husband and wife, are ambushed and killed by Tine fanatics known as Flenserists, in whose realm they have landed. The Flenserists capture a young boy named Jefri Olsndot and his wounded sister, Johanna. Johanna is rescued by a Tine named Pilgrim who witnessed the ambush and taken to a neighboring kingdom ruled by a brilliant Tine named Woodcarver. Steel, the Flenserists' leader, tells Jefri that Johanna and their parents were killed by Woodcarver and exploits him in order to develop advanced technology (such as cannon and radio communication), while Johanna and the knowledge stored in her "dataset" device help Woodcarver rapidly develop as well. A highly placed Flenserist spy keeps Steel informed of Woodcarver's progress.
A distress signal from the sleeper ship eventually reaches "Relay", a major information/service provider for the galactic communications network. A benign transcendent being named "the Old One" contacts Relay, seeking information about the Blight and the humans who released it, and reconstitutes a human man named Pham Nuwen from the wreckage of a spaceship to act as its agent, using his doubt of his own memory's veracity to keep him under its control. Ravna Bergsndot, the only human Relay employee, traces the sleeper ship's signal to the Tines' world and persuades her employer to investigate what it took from High Lab, contracting the merchant vessel "Out of Band II", owned by two sentient plant "Skroderiders", Blueshell and Greenstalk, to transport her and Pham there.
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Before the mission is launched, the Blight launches a surprise attack on Relay and kills Old One. As Old One dies, it downloads what information it can into Pham to defeat the Blight, and Pham, Ravna and the Skroderiders barely escape Relay's destruction in the "Out of Band II".
The Blight expands, taking over races and "rewriting" their people to become its agents, murdering several other Powers, and seizing other archives in the Beyond, looking for what was taken. It finally realizes where the danger truly lies and sends a hastily assembled fleet in pursuit.
The humans arrive at the Tines' homeworld first and ally with Woodcarver to defeat the Flenserists and rescue Jefri. Pham initiates Countermeasure, which extends the Slow Zone outward by thousands of light years, enveloping and killing the Blight at the cost of wrecking thousands of civilizations and causing trillions of deaths. The humans are stranded on the Tines world, now in the depths of the Slow Zone. Activating Countermeasure is fatal to Pham, but before he dies, the ghost of Old One within his mind reveals to him that, although his body is a reconstruction, his memories are real. (Vinge expands on Pham's backstory in "A Deepness in the Sky".)
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Intelligent species.
Aprahanti.
A race of humanoids with colorful butterfly-like wings who attempt to use the chaos wrought by the Blight to reestablish their waning hegemony. Despite their attractive, delicate appearance, the Aprahanti are an extremely fearsome and vicious species.
Blight.
An ancient, malevolent super-intelligent entity which strives to constantly expand and can easily manipulate electronics and organic beings.
Dirokimes.
An older race which originally inhabited Sjandra Kei before the arrival of humanity. They work with the humans.
Humans.
All humans in the novel (except Pham) are descended from Nyjoran stock. Their ancestors were "Tuvo-Norsk" asteroid miners from Old Earth's solar system, which is noted as being on the other side of the galaxy in the Slow Zone. ("Nyjora" sounds similar to New Norwegian "New Earth".) One of the major human habitations is Sjandra Kei, three systems comprising roughly 28 billion individuals. Their main language is Samnorsk, the Norwegian term for a hypothetical unification of the Bokmål and Nynorsk forms of the language. (Vinge indicates in the book's dedication that several key ideas in it came to him while at a conference in Tromsø, Norway.)
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