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3,301 | Some early optical drives have dedicated buttons for CD playback controls on their front panel, allowing them to act as a standalone compact disc player. |
3,302 | External drives were popular in the beginning, because the drives often required complex electronics to institute, rivaling in complexity the Host computer system itself. External drives using SCSI, Parallel port, USB and FireWire interfaces exist, most modern drives being USB. Some portable versions for laptops power ... |
3,303 | Drives with a SCSI interface were originally the only system interface available, but they never became popular in the price sensitive low-end consumer market which constituted majority of the demand. They were less common and tended to be more expensive, because of the cost of their interface chipsets, more complex SC... |
3,304 | When the optical disc drive was first developed, it was not easy to add to computer systems. Some computers such as the IBM PS/2 were standardizing on the 3+1⁄2-inch floppy and 3+1⁄2-inch hard disk and did not include a place for a large internal device. Also IBM PCs and clones at first only included a single ATA driv... |
3,305 | This was solved through several techniques: |
3,306 | Due to lack of asynchrony in existing implementations, an optical drive encountering damaged sectors may cause computer programs trying to access the drives, such as Windows Explorer, to lock up. |
3,307 | Drive models may support adjustment of behavioural parameters for performance optimization and testing purposes, such as the read retry count , write retry count , and the option to deactivate error correction . For example, the read retry count specifies how often the drive should attempt reading a damaged sector. A h... |
3,308 | The sdparm command-line utility allows manually controlling such parameters. For example, sdparm --set RRC=10 /dev/sr0 sets the read retry count to 10 for the optical drive device file "sr0", and sdparm --all /dev/sr0 lists all code pages. The values may be interpreted varyingly among drive models or vendors. |
3,309 | The optical drives in the photos are shown right side up; the disc would sit on top of them. The laser and optical system scans the underside of the disc. |
3,310 | With reference to the top photo, just to the right of image center is the disc motor, a metal cylinder, with a gray centering hub and black rubber drive ring on top. There is a disc-shaped round clamp, loosely held inside the cover and free to rotate; it's not in the photo. After the disc tray stops moving inward, as t... |
3,311 | Two parallel guide rods that run between upper left and lower right in the photo carry the "sled", the moving optical read-write head. As shown, this "sled" is close to, or at the position where it reads or writes at the edge of the disc. To move the "sled" during continuous read or write operations, a stepper motor ro... |
3,312 | In contrast, the mechanism shown in the second photo, which comes from a cheaply made DVD player, uses less accurate and less efficient brushed DC motors to both move the sled and spin the disc. Some older drives use a DC motor to move the sled, but also have a magnetic rotary encoder to keep track of the position. Mos... |
3,313 | The gray metal chassis is shock-mounted at its four corners to reduce sensitivity to external shocks, and to reduce drive noise from residual imbalance when running fast. The soft shock mount grommets are just below the brass-colored screws at the four corners . |
3,314 | In the third photo, the components under the cover of the lens mechanism are visible. The two permanent magnets on either side of the lens holder as well as the coils that move the lens can be seen. This allows the lens to be moved up, down, forwards, and backwards to stabilize the focus of the beam. |
3,315 | In the fourth photo, the inside of the optics package can be seen. Note that since this is a CD-ROM drive, there is only one laser, which is the black component mounted to the bottom left of the assembly. Just above the laser are the first focusing lens and prism that direct the beam at the disc. The tall, thin object ... |
3,316 | The irregular orange material is flexible etched copper foil supported by thin sheet plastic; these are "flexible circuits" that connect everything to the electronics . |
3,317 | The first laser disc, demonstrated in 1972, was the Laservision 12-inch video disc. The video signal was stored as an analog format like a video cassette. The first digitally recorded optical disc was a 5-inch audio compact disc in a read-only format created by Sony and Philips in 1975. |
3,318 | The first erasable optical disc drives were announced in 1983, by Matsushita , Sony, and Kokusai Denshin Denwa . Sony eventually released the first commercial erasable and rewritable 5+1⁄4-inch optical disc drive in 1987, with dual-sided discs capable of holding 325 MB per side. |
3,319 | The CD-ROM format was developed by Sony and Denon, introduced in 1984, as an extension of Compact Disc Digital Audio and adapted to hold any form of digital data. The CD-ROM format has a storage capacity of 650 MB. Also in 1984, Sony introduced a LaserDisc data storage format, with a larger data capacity of 3.28 GB. |
3,320 | In September 1992, Sony announced the MiniDisc format, which was supposed to combine the audio clarity of CD's and the convenience of a cassette size. The standard capacity holds 80 minutes of audio. In January 2004, Sony revealed an upgraded Hi-MD format, which increased the capacity to 1 GB . |
3,321 | The DVD format, developed by Panasonic, Sony, and Toshiba, was released in 1995, and was capable of holding 4.7 GB per layer; with the first DVD players shipping on November 1, 1996, by Panasonic and Toshiba in Japan and the first DVD-ROM compatible computers being shipped on November 6 of that year by Fujitsu. Sales o... |
3,322 | In 1999, Kenwood released a multi-beam optical drive that achieved burning speeds as high as 72×, which would require dangerous spinning speeds to attain with single-beam burning. However, it suffered from reliability issues. |
3,323 | The first Blu-ray prototype was unveiled by Sony in October 2000, and the first commercial recording device was released to market on April 10, 2003. In January 2005, TDK announced that they had developed an ultra-hard yet very thin polymer coating for Blu-ray Discs; this was a significant technical advance because be... |
3,324 | Starting in the mid-2010s, computer manufacturers began to stop including built-in optical disc drives on their products, with the advent of cheap, rugged , fast and high capacity USB drives and video on demand over the internet. Excluding an optical drive allows for circuit boards in laptops to be larger and less dens... |
3,325 | Most optical drives are backward compatible with their ancestors up to CD, although this is not required by standards. |
3,326 | Compared to a CD's 1.2 mm layer of polycarbonate, a DVD's laser beam only has to penetrate 0.6 mm in order to reach the recording surface. This allows a DVD drive to focus the beam on a smaller spot size and to read smaller pits. DVD lens supports a different focus for CD or DVD media with same laser. With the newer B... |
3,327 | During the times of CD writer drives, they are often marked with three different speed ratings. In these cases, the first speed is for write-once operations, the second speed for re-write operations, and the last speed for read-only operations. For example, a 40×/16×/48× CD writer drive is capable of writing to CD-R... |
3,328 | During the times of combo drives, an additional speed rating is designated for DVD-ROM media reading operations. |
3,329 | For DVD writer drives, Blu-ray Disc combo drives, and Blu-ray Disc writer drives, the writing and reading speed of their respective optical media are specified in its retail box, user's manual, or bundled brochures or pamphlets. |
3,330 | In the late 1990s, buffer underruns became a very common problem as high-speed CD recorders began to appear in home and office computers, which—for a variety of reasons—often could not muster the I/O performance to keep the data stream to the recorder steadily fed. The recorder, should it run short, would be forced to ... |
3,331 | In response, manufacturers of CD recorders began shipping drives with "buffer underrun protection" . These can suspend and resume the recording process in such a way that the gap the stoppage produces can be dealt with by the error-correcting logic built into CD players and CD-ROM drives. The first of these drives wer... |
3,332 | The first optical drive to support recording DVDs at 16× speed was the Pioneer DVR-108, released in the second half of 2004. At that time however, no recordable DVD media supported that high recording speed yet. |
3,333 | While drives are burning DVD+R, DVD+RW and all Blu-ray formats, they do not require any such error correcting recovery as the recorder is able to place the new data exactly on the end of the suspended write effectively producing a continuous track . Although later interfaces were able to stream data at the required sp... |
3,334 | The internal buffer of optical disc writer drives is: 8 MiB or 4 MiB when recording BD-R, BD-R DL, BD-RE, or BD-RE DL media; 2 MiB when recording DVD-R, DVD-RW, DVD-R DL, DVD+R, DVD+RW, DVD+RW DL, DVD-RAM, CD-R, or CD-RW media. |
3,335 | CD recording on personal computers was originally a batch-oriented task in that it required specialised authoring software to create an "image" of the data to record and to record it to disc in the one session. This was acceptable for archival purposes, but limited the general convenience of CD-R and CD-RW discs as a r... |
3,336 | Packet writing is a scheme in which the recorder writes incrementally to disc in short bursts, or packets. Sequential packet writing fills the disc with packets from bottom up. To make it readable in CD-ROM and DVD-ROM drives, the disc can be closed at any time by writing a final table-of-contents to the start of the d... |
3,337 | Fixed-length packet writing divides up the disc into padded, fixed-size packets. The padding reduces the capacity of the disc, but allows the recorder to start and stop recording on an individual packet without affecting its neighbours. These resemble the block-writable access offered by magnetic media closely enough... |
3,338 | The DVD+RW disc format eliminates this unreliability by embedding more accurate timing hints in the data groove of the disc and allowing individual data blocks to be replaced without affecting backward compatibility . The format itself was designed to deal with discontinuous recording because it was expected to be wid... |
3,339 | Mount Rainier aims to make packet-written CD-RW and DVD+RW discs as convenient to use as that of removable magnetic media by having the firmware format new discs in the background and manage media defects . As of February 2007, support for Mount Rainier is natively supported in Windows Vista. All previous versions of... |
3,340 | Owing to pressure from the music industry, as represented by the IFPI and RIAA, Philips developed the Recorder Identification Code to allow media to be uniquely associated with the recorder that has written it. This standard is contained in the Rainbow Books. The RID-Code consists of a supplier code , a model number a... |
3,341 | Although the RID was introduced for music and video industry purposes, the RID is included on every disc written by every drive, including data and backup discs. The value of the RID is questionable as it is impossible to locate any individual recorder due to there being no database. |
3,342 | The Source Identification Code is an eight character supplier code that is placed on optical discs by the manufacturer. The SID identifies not only manufacturer, but also the individual factory and machine that produced the disc. |
3,343 | According to Phillips, the administrator of the SID codes, the SID code provides an optical disc production facility with the means to identify all discs mastered or replicated in its plant, including the specific Laser Beam Recorder signal processor or mould that produced a particular stamper or disc. |
3,344 | The standard use of RID and SID mean that each disc written contains a record of the machine that produced a disc , and which drive wrote it . This combined knowledge may be very useful to law enforcement, to investigative agencies, and to private or corporate investigators. |
3,345 | A significant motivation for introducing the SID code was to identify disc manufacturing plants producing unauthorised copies of commercial CDs. By the 1990s, the production process for CDs had evolved from requiring a "clean-room" environment involving multiple processes, this demanding a substantial investment and li... |
3,346 | A floppy disk or floppy diskette is a type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined with a fabric that removes dust particles from the spinning disk. Floppy disks store digital data which can be read and written when the disk... |
3,347 | The first floppy disks, invented and made by IBM, had a disk diameter of 8 inches . Subsequently, the 5¼-inch and then the 3½-inch became a ubiquitous form of data storage and transfer into the first years of the 21st century. 3½-inch floppy disks can still be used with an external USB floppy disk drive. USB drives f... |
3,348 | Floppy disks were so common in late 20th-century culture that many electronic and software programs continue to use save icons that look like floppy disks well into the 21st century, as a form of skeuomorphic design. While floppy disk drives still have some limited uses, especially with legacy industrial computer equip... |
3,349 | The first commercial floppy disks, developed in the late 1960s, were 8 inches in diameter; they became commercially available in 1971 as a component of IBM products and both drives and disks were then sold separately starting in 1972 by Memorex and others. These disks and associated drives were produced and improved u... |
3,350 | In 1976, Shugart Associates introduced the 5¼-inch FDD. By 1978, there were more than ten manufacturers producing such FDDs. There were competing floppy disk formats, with hard- and soft-sector versions and encoding schemes such as differential Manchester encoding , modified frequency modulation , M2FM and group coded ... |
3,351 | Throughout the early 1980s, limits of the 5¼-inch format became clear. Originally designed to be more practical than the 8-inch format, it was becoming considered too large; as the quality of recording media grew, data could be stored in a smaller area. Several solutions were developed, with drives at 2-, 2½-, 3-, 3¼-,... |
3,352 | Generally, the term floppy disk persisted, even though later style floppy disks have a rigid case around an internal floppy disk. |
3,353 | By the end of the 1980s, 5¼-inch disks had been superseded by 3½-inch disks. During this time, PCs frequently came equipped with drives of both sizes. By the mid-1990s, 5¼-inch drives had virtually disappeared, as the 3½-inch disk became the predominant floppy disk. The advantages of the 3½-inch disk were its higher ca... |
3,354 | Floppy disks became commonplace during the 1980s and 1990s in their use with personal computers to distribute software, transfer data, and create backups. Before hard disks became affordable to the general population, floppy disks were often used to store a computer's operating system . Most home computers from that ti... |
3,355 | By the early 1990s, the increasing software size meant large packages like Windows or Adobe Photoshop required a dozen disks or more. In 1996, there were an estimated five billion standard floppy disks in use. |
3,356 | An attempt to enhance the existing 3½-inch designs was the SuperDisk in the late 1990s, using very narrow data tracks and a high precision head guidance mechanism with a capacity of 120 MB and backward-compatibility with standard 3½-inch floppies; a format war briefly occurred between SuperDisk and other high-density f... |
3,357 | In the mid-1990s, mechanically incompatible higher-density floppy disks were introduced, like the Iomega Zip disk. Adoption was limited by the competition between proprietary formats and the need to buy expensive drives for computers where the disks would be used. In some cases, failure in market penetration was exacer... |
3,358 | Apple introduced the iMac G3 in 1998 with a CD-ROM drive but no floppy drive; this made USB-connected floppy drives popular accessories, as the iMac came without any writable removable media device. |
3,359 | Recordable CDs were touted as an alternative, because of the greater capacity, compatibility with existing CD-ROM drives, and—with the advent of re-writeable CDs and packet writing—a similar reusability as floppy disks. However, CD-R/RWs remained mostly an archival medium, not a medium for exchanging data or editing fi... |
3,360 | Flash-based USB-thumb drives finally were a practical and popular replacement, that supported traditional file systems and all common usage scenarios of floppy disks. As opposed to other solutions, no new drive type or special software was required that impeded adoption, since all that was necessary was an already comm... |
3,361 | By 2002, most manufacturers still provided floppy disk drives as standard equipment to meet user demand for file-transfer and an emergency boot device, as well as for the general secure feeling of having the familiar device. By this time, the retail cost of a floppy drive had fallen to around $20 , so there was little ... |
3,362 | Floppy disks are used for emergency boots in aging systems lacking support for other bootable media and for BIOS updates, since most BIOS and firmware programs can still be executed from bootable floppy disks. If BIOS updates fail or become corrupt, floppy drives can sometimes be used to perform a recovery. The music a... |
3,363 | In May 2016, the United States Government Accountability Office released a report that covered the need to upgrade or replace legacy computer systems within federal agencies. According to this document, old IBM Series/1 minicomputers running on 8-inch floppy disks are still used to coordinate "the operational functions... |
3,364 | Windows 10 and Windows 11 no longer come with drivers for floppy disk drives . However, they will still support them with a separate device driver provided by Microsoft. |
3,365 | The British Airways Boeing 747-400 fleet, up to its retirement in 2020, used 3½-inch floppy disks to load avionics software. |
3,366 | Sony, who had been in the floppy disk business since 1983, ended domestic sales of all six 3½-inch floppy disk models as of March 2011. This has been viewed by some as the end of the floppy disk. While production of new floppy disk media has ceased, sales and uses of this media from inventories is expected to continue ... |
3,367 | For more than two decades, the floppy disk was the primary external writable storage device used. Most computing environments before the 1990s were non-networked, and floppy disks were the primary means to transfer data between computers, a method known informally as sneakernet. Unlike hard disks, floppy disks are hand... |
3,368 | The 8-inch and 5¼-inch floppy disks contain a magnetically coated round plastic medium with a large circular hole in the center for a drive's spindle. The medium is contained in a square plastic cover that has a small oblong opening in both sides to allow the drive's heads to read and write data and a large hole in the... |
3,369 | Inside the cover are two layers of fabric with the magnetic medium sandwiched in the middle. The fabric is designed to reduce friction between the medium and the outer cover, and catch particles of debris abraded off the disk to keep them from accumulating on the heads. The cover is usually a one-part sheet, double-fol... |
3,370 | A small notch on the side of the disk identifies that it is writable, detected by a mechanical switch or phototransistor above it; if it is not present, the disk can be written; in the 8-inch disk the notch is covered to enable writing while in the 5¼-inch disk the notch is open to enable writing. Tape may be used over... |
3,371 | Another LED/photo-transistor pair located near the center of the disk detects the index hole once per rotation in the magnetic disk; it is used to detect the angular start of each track and whether or not the disk is rotating at the correct speed. Early 8‑inch and 5¼‑inch disks had physical holes for each sector and we... |
3,372 | The core of the 3½-inch disk is the same as the other two disks, but the front has only a label and a small opening for reading and writing data, protected by the shutter—a spring-loaded metal or plastic cover, pushed to the side on entry into the drive. Rather than having a hole in the center, it has a metal hub which... |
3,373 | Two holes at the bottom left and right indicate whether the disk is write-protected and whether it is high-density; these holes are spaced as far apart as the holes in punched A4 paper, allowing write-protected high-density floppies to be clipped into standard ring binders. The dimensions of the disk shell are not quit... |
3,374 | One of the chief usability problems of the floppy disk is its vulnerability; even inside a closed plastic housing, the disk medium is highly sensitive to dust, condensation and temperature extremes. As with all magnetic storage, it is vulnerable to magnetic fields. Blank disks have been distributed with an extensive se... |
3,375 | A spindle motor in the drive rotates the magnetic medium at a certain speed, while a stepper motor-operated mechanism moves the magnetic read/write heads radially along the surface of the disk. Both read and write operations require the media to be rotating and the head to contact the disk media, an action originally a... |
3,376 | A blank unformatted diskette has a coating of magnetic oxide with no magnetic order to the particles. During formatting, the magnetizations of the particles are aligned forming tracks, each broken up into sectors, enabling the controller to properly read and write data. The tracks are concentric rings around the center... |
3,377 | Each sector of data has a header that identifies the sector location on the disk. A cyclic redundancy check is written into the sector headers and at the end of the user data so that the disk controller can detect potential errors. |
3,378 | Some errors are soft and can be resolved by automatically re-trying the read operation; other errors are permanent and the disk controller will signal a failure to the operating system if multiple attempts to read the data still fail. |
3,379 | After a disk is inserted, a catch or lever at the front of the drive is manually lowered to prevent the disk from accidentally emerging, engage the spindle clamping hub, and in two-sided drives, engage the second read/write head with the media. |
3,380 | In some 5¼-inch drives, insertion of the disk compresses and locks an ejection spring which partially ejects the disk upon opening the catch or lever. This enables a smaller concave area for the thumb and fingers to grasp the disk during removal. |
3,381 | Newer 5¼-inch drives and all 3½-inch drives automatically engage the spindle and heads when a disk is inserted, doing the opposite with the press of the eject button. |
3,382 | On Apple Macintosh computers with built-in 3½-inch disk drives, the ejection button is replaced by software controlling an ejection motor which only does so when the operating system no longer needs to access the drive. The user could drag the image of the floppy drive to the trash can on the desktop to eject the disk.... |
3,383 | Before a disk can be accessed, the drive needs to synchronize its head position with the disk tracks. In some drives, this is accomplished with a Track Zero Sensor, while for others it involves the drive head striking an immobile reference surface. |
3,384 | In either case, the head is moved so that it is approaching track zero position of the disk. When a drive with the sensor has reached track zero, the head stops moving immediately and is correctly aligned. For a drive without the sensor, the mechanism attempts to move the head the maximum possible number of positions n... |
3,385 | Some drive mechanisms such as the Apple II 5¼-inch drive without a track zero sensor, produce characteristic mechanical noises when trying to move the heads past the reference surface. This physical striking is responsible for the 5¼-inch drive clicking during the boot of an Apple II, and the loud rattles of its DOS an... |
3,386 | All 8-inch and some 5¼-inch drives used a mechanical method to locate sectors, known as either hard sectors or soft sectors, and is the purpose of the small hole in the jacket, off to the side of the spindle hole. A light beam sensor detects when a punched hole in the disk is visible through the hole in the jacket. |
3,387 | For a soft-sectored disk, there is only a single hole, which is used to locate the first sector of each track. Clock timing is then used to find the other sectors behind it, which requires precise speed regulation of the drive motor. |
3,388 | For a hard-sectored disk, there are many holes, one for each sector row, plus an additional hole in a half-sector position, that is used to indicate sector zero. |
3,389 | The Apple II computer system is notable in that it did not have an index hole sensor and ignored the presence of hard or soft sectoring. Instead, it used special repeating data synchronization patterns written to the disk between each sector, to assist the computer in finding and synchronizing with the data in each tra... |
3,390 | The later 3½-inch drives of the mid-1980s did not use sector index holes, but instead also used synchronization patterns. |
3,391 | Most 3½-inch drives used a constant speed drive motor and contain the same number of sectors across all tracks. This is sometimes referred to as Constant Angular Velocity . In order to fit more data onto a disk, some 3½-inch drives instead use Constant Linear Velocity , which uses a variable speed drive motor that spi... |
3,392 | While the original IBM 8-inch disk was actually so defined, the other sizes are defined in the metric system, their usual names being but rough approximations. |
3,393 | Different sizes of floppy disks are mechanically incompatible, and disks can fit only one size of drive. Drive assemblies with both 3½-inch and 5¼-inch slots were available during the transition period between the sizes, but they contained two separate drive mechanisms. In addition, there are many subtle, usually softw... |
3,394 | Floppy disks of the first standard are 8 inches in diameter, protected by a flexible plastic jacket. It was a read-only device used by IBM as a way of loading microcode. Read/write floppy disks and their drives became available in 1972, but it was IBM's 1973 introduction of the 3740 data entry system that began the est... |
3,395 | The family of 8-inch disks and drives increased over time and later versions could store up to 1.2 MB; many microcomputer applications did not need that much capacity on one disk, so a smaller size disk with lower-cost media and drives was feasible. The 5¼-inch drive succeeded the 8-inch size in many applications, and ... |
3,396 | The head gap of an 80‑track high-density 5¼‑inch drive is smaller than that of a 40‑track double-density drive but can also format, read and write 40‑track disks provided the controller supports double stepping or has a switch to do so. 5¼-inch 80-track drives were also called hyper drives. A blank 40‑track disk for... |
3,397 | Single-sided disks were coated on both sides, despite the availability of more expensive double sided disks. The reason usually given for the higher price was that double sided disks were certified error-free on both sides of the media. Double-sided disks could be used in some drives for single-sided disks, as long as ... |
3,398 | In the early 1980s, many manufacturers introduced smaller floppy drives and media in various formats. A consortium of 21 companies eventually settled on a 3½-inch design known as the Micro diskette, Micro disk, or Micro floppy, similar to a Sony design but improved to support both single-sided and double-sided media, w... |
3,399 | All 3½-inch disks have a rectangular hole in one corner which, if obstructed, write-enables the disk. A sliding detented piece can be moved to block or reveal the part of the rectangular hole that is sensed by the drive. The HD 1.44 MB disks have a second, unobstructed hole in the opposite corner that identifies them a... |
3,400 | In IBM-compatible PCs, the three densities of 3½-inch floppy disks are backwards-compatible; higher-density drives can read, write and format lower-density media. It is also possible to format a disk at a lower density than that for which it was intended, but only if the disk is first thoroughly demagnetized with a bul... |
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