HDTenEightyP/CompuServe · Datasets at Hugging Face

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your letter will look a little better on the screen.
*ln2
The Dictionary Page-16
*ln2
Blazin' Forth normally allows 31 characters to be saved in a definitions name. (This is the number specified by the 83 standard.) However, should you prefer fewer characters to be saved, you can do this by changing the value of the variable WIDTH . For example, to have Blazin' Forth save only three characters of your definitions names, type 3 WIDTH !
*ln2
Say-What?
*ln2
Regarding the second foot-note on page-18. The Forth-83 ." will not execute outside of a colon definition. Forth-83 provides the word .( for the occasions when you need to display strings outside of colon definitions. Use it like this:

.( PRINT ME )
*ln2
cn1;Chapter-2cn0
*ln2
The handy hint on page-50 is a little notorious. I have, personally, never seen a system on which this definition would work. .S is never the less a very handy word, and Blazin' Forth contains it, already compiled into the system. Note that the extra 0 won't be there - you see only what's on the stack, or you get a message "STACK EMPTY", if nothing is on the stack.
*ln2
cn1;Chapter-3cn0
*ln2
Blazin' Forth's editor is a "Starting-Forth-Clone". You will be able to follow this chapter pretty much as it stands. One very important point - you must issue the command MOUNT , to initialize the virtual memory system, before using any words that access the disk - like LIST , for example. Just remember to type MOUNT , and you will be OK . (You only have to give this command once - at the start of your editing session, unless you change disks, issue the command RESTART, or inadvertantly cause a disk error.)
Some general points: Brodie likes to keep his screen numbers high - in the 100's or 200's . Note that if you have a dual drive, such as a 4040 or MSD , you will have no problem with these high screen numbers ( of course, you will have to have a disk in drive 1!). However, if you are using the system with a single disk drive, such as a 1541, then the highest screen that can be accessed from that drive is 165 . Just keep all your screen numbers below this value, and you will be OK .
The WIPE command is very important, never edit a new screen without using this command first! It's so important, that Blazin Forth contains the word W , which is just a short way to perform a WIPE . Works just the same.
Finally, due to the characteristics of the 64's operating system, trailing blanks are suppressed, and not passed to the editor. This means, for example, that Brodies example of blanking a line:

P bb <return>

won't work. Trailing blanks must be followed by an ^ character in order to be received by the editor. For example:

P bb^ ( blanks current line )
U bb^ ( blanks line under current line)

That's enough for now - check back here when you get to FLUSH.

In Forth-83, FLUSH and SAVE-BUFFERS are not quite the same. Both save any updated blocks to the disk, but FLUSH will "hose down" the buffers - if you want to access the same blocks again, Forth will have to re-read them. SAVE-BUFFERS will leave all the blocks current - Forth won't have to re-read them if you need to access them again. Also, Blazin' Forth contains an additional comment word, // , which can be used to include 1 line comments in source screens.
*ln2
Getting Loaded Page-81
*ln2
The suggestion here is not really very good. If the source for your text takes up more than one block, the best solution is not to use many load commands, as Brodie suggests, but to use THRU .
THRU takes two numbers on the stack. The first number is the first screen to load, and the second number is the last screen to load. THRU will then load these two screens, and all screens in between.
So, instead of putting 180 LOAD 181 LOAD 182 LOAD on your load screen, use:

180 182 THRU

instead. It's really much better.
*ln3
cn1;Chapter 4cn0
*ln3
A Closer Look at IF . Page-95

One of the big differences between the 83 standard and earlier Forths is that Forth-83 returns a negative 1 ( -1 ) instead of 1 when the result of a test like 0= or 0< is true. So Brodies examples will look like this:

5 4 > . -1 OK
5 4 < . 0 OK

NOT works differently too. In earlier Forths, it was really just another name for 0= . But in Forth-83, it returns the ones-compliment of the number on the top of the stack. Notice that the '83 NOT still reverses the value of the '83 flags:*ln2
-1 NOT . 0 OK
0 NOT . -1 OK
*ln2
But NOT won't change any non-zero value to false ( 0 ) like the older NOT would:*ln2
1 NOT . -2 OK
*ln2
And, of course, FORTH will still regard -2 as being TRUE , since it isn't zero.

So when upgrading programs, or reading books that talk about earlier Forth systems, keep this in mind. On the other hand, if you're not quite sure what all this means, and want to play it safe, just replace every pre-83 NOT with 0= , and you'll be OK .
*ln2
A Little Logic Page-97
*ln2
To upgrade these examples to FORTH-83, just replace every occurance of 1 with -1 , and you'll have a Forth-83 example. While we are on the subject, Blazin' Forth contains the two flags pre-compiled as constants. TRUE leaves a true value (-1) on the top of the stack, and FALSE leaves a false value ( 0 ). You'll appreciate this more when you learn about constants later in the book.
*ln2
Two Words with built in IFs Page 102
*ln2
Just a note - if you do want to add stack checking to your application, all you need to add in Blazin' Forth is the word ?STACK . The ABORT" isn't needed, since ?STACK itself contains the necessary ABORT" .
*ln2
Problems Page-104
*ln2
Problem 5
Actually, in Forth-83, 0 STARS won't print just one star, but 65,535 stars. Brodies answer ( or the one you cook up for yourself) should fix this problem, but there are better ways. More on this when we get to the chapter on LOOPs. Incidentally, if you tried 0 STARS before reading this note, you can get control of things by hitting RUN/STOP RESTORE , just like in BASIC .
*ln2
Chapter-5

The Return Stack

Page-110

The definitions for I , I' and J are not correct for Forth-83. I' does not exist, and I and J are both defined differently. Don't worry, they still do what they are supposed to (which is return the current index value of a loop), it's just that they don't do what Brodie says they would. Just wait till chapter 6 for more information on these two words.

The correct word to copy the top of the return stack is R@ in Forth-83. (i.e. R@ does what Brodie says I should do.)

Page-111

The phrase >R SWAP I would be >R SWAP R@ in Forth - 83. Both phrases will crash the system

Page-112

The definition of QUADRATIC should be:

: QUADRATIC ( A B C X -- N )
>R SWAP ROT R@ * + R> * + ;

In other words, R@ should be used instead of I . See the note above for an explanation.

your letter will look a little better on the screen.

*ln2

The Dictionary Page-16

*ln2

Blazin' Forth normally allows 31 characters to be saved in a definitions name. (This is the number specified by the 83 standard.) However, should you prefer fewer characters to be saved, you can do this by changing the value of the variable WIDTH . For example, to have Blazin' Forth save only three characters of your definitions names, type 3 WIDTH !

*ln2

Say-What?

*ln2

Regarding the second foot-note on page-18. The Forth-83 ." will not execute outside of a colon definition. Forth-83 provides the word .( for the occasions when you need to display strings outside of colon definitions. Use it like this:

.( PRINT ME )

*ln2

*cn1;Chapter-2*cn0

*ln2

The handy hint on page-50 is a little notorious. I have, personally, never seen a system on which this definition would work. .S is never the less a very handy word, and Blazin' Forth contains it, already compiled into the system. Note that the extra 0 won't be there - you see only what's on the stack, or you get a message "STACK EMPTY", if nothing is on the stack.

*ln2

*cn1;Chapter-3*cn0

*ln2

Blazin' Forth's editor is a "Starting-Forth-Clone". You will be able to follow this chapter pretty much as it stands. One very important point - you must issue the command MOUNT , to initialize the virtual memory system, before using any words that access the disk - like LIST , for example. Just remember to type MOUNT , and you will be OK . (You only have to give this command once - at the start of your editing session, unless you change disks, issue the command RESTART, or inadvertantly cause a disk error.)

Some general points: Brodie likes to keep his screen numbers high - in the 100's or 200's . Note that if you have a dual drive, such as a 4040 or MSD , you will have no problem with these high screen numbers ( of course, you will have to have a disk in drive 1!). However, if you are using the system with a single disk drive, such as a 1541, then the highest screen that can be accessed from that drive is 165 . Just keep all your screen numbers below this value, and you will be OK .

The WIPE command is very important, never edit a new screen without using this command first! It's so important, that Blazin Forth contains the word W , which is just a short way to perform a WIPE . Works just the same.

Finally, due to the characteristics of the 64's operating system, trailing blanks are suppressed, and not passed to the editor. This means, for example, that Brodies example of blanking a line:

P bb <return>

won't work. Trailing blanks must be followed by an ^ character in order to be received by the editor. For example:

P bb^ ( blanks current line )

U bb^ ( blanks line under current line)

That's enough for now - check back here when you get to FLUSH.

In Forth-83, FLUSH and SAVE-BUFFERS are not quite the same. Both save any updated blocks to the disk, but FLUSH will "hose down" the buffers - if you want to access the same blocks again, Forth will have to re-read them. SAVE-BUFFERS will leave all the blocks current - Forth won't have to re-read them if you need to access them again. Also, Blazin' Forth contains an additional comment word, // , which can be used to include 1 line comments in source screens.

*ln2

Getting Loaded Page-81

*ln2

The suggestion here is not really very good. If the source for your text takes up more than one block, the best solution is not to use many load commands, as Brodie suggests, but to use THRU .

THRU takes two numbers on the stack. The first number is the first screen to load, and the second number is the last screen to load. THRU will then load these two screens, and all screens in between.

So, instead of putting 180 LOAD 181 LOAD 182 LOAD on your load screen, use:

180 182 THRU

instead. It's really much better.

*ln3

*cn1;Chapter 4*cn0

*ln3

A Closer Look at IF . Page-95

One of the big differences between the 83 standard and earlier Forths is that Forth-83 returns a negative 1 ( -1 ) instead of 1 when the result of a test like 0= or 0< is true. So Brodies examples will look like this:

5 4 > . -1 OK

5 4 < . 0 OK

NOT works differently too. In earlier Forths, it was really just another name for 0= . But in Forth-83, it returns the ones-compliment of the number on the top of the stack. Notice that the '83 NOT still reverses the value of the '83 flags:*ln2

-1 NOT . 0 OK

0 NOT . -1 OK

*ln2

But NOT won't change any non-zero value to false ( 0 ) like the older NOT would:*ln2

1 NOT . -2 OK

*ln2

And, of course, FORTH will still regard -2 as being TRUE , since it isn't zero.

So when upgrading programs, or reading books that talk about earlier Forth systems, keep this in mind. On the other hand, if you're not quite sure what all this means, and want to play it safe, just replace every pre-83 NOT with 0= , and you'll be OK .

*ln2

A Little Logic Page-97

*ln2

To upgrade these examples to FORTH-83, just replace every occurance of 1 with -1 , and you'll have a Forth-83 example. While we are on the subject, Blazin' Forth contains the two flags pre-compiled as constants. TRUE leaves a true value (-1) on the top of the stack, and FALSE leaves a false value ( 0 ). You'll appreciate this more when you learn about constants later in the book.

*ln2

Two Words with built in IFs Page 102

*ln2

Just a note - if you do want to add stack checking to your application, all you need to add in Blazin' Forth is the word ?STACK . The ABORT" isn't needed, since ?STACK itself contains the necessary ABORT" .

*ln2

Problems Page-104

*ln2

Problem 5

Actually, in Forth-83, 0 STARS won't print just one star, but 65,535 stars. Brodies answer ( or the one you cook up for yourself) should fix this problem, but there are better ways. More on this when we get to the chapter on LOOPs. Incidentally, if you tried 0 STARS before reading this note, you can get control of things by hitting RUN/STOP RESTORE , just like in BASIC .

*ln2

Chapter-5

The Return Stack

Page-110

The definitions for I , I' and J are not correct for Forth-83. I' does not exist, and I and J are both defined differently. Don't worry, they still do what they are supposed to (which is return the current index value of a loop), it's just that they don't do what Brodie says they would. Just wait till chapter 6 for more information on these two words.

The correct word to copy the top of the return stack is R@ in Forth-83. (i.e. R@ does what Brodie says I should do.)

Page-111

The phrase >R SWAP I would be >R SWAP R@ in Forth - 83. Both phrases will crash the system

Page-112

The definition of QUADRATIC should be:

: QUADRATIC ( A B C X -- N )

>R SWAP ROT R@ * + R> * + ;

In other words, R@ should be used instead of I . See the note above for an explanation.