!!! MESA FORTH for Atari 8Bit Handbook
[{TableOfContents }]
!! Chapter 1
! Introduction
MesaForth is based on the 6502 fig-Forth model. The major
difference from the model is in the size of the screen on disk
(512 bytes instead of 1024 bytes). You should refer to fig-Forth
documentation for a complete description of Forth and the standard
words provided in fig-Forth. This document will describe the
special features provided in MesaForth.
A major difference between MesaForth and other Forth's
available for ATARI is that MesaForth runs under ATARI DOS 2.0S.
Forth source files and data files are written on standard DOS
formatted diskettes. This means that Forth files can be
interchanged with any other program that uses DOS files (ATARI
BASIC, Assembler/Editor, Music Composer, ATARI Word Processor,
etc.). This can make MesaForth a powerful tool in producing
efficient software on your ATARI.
Your MesaForth system diskette contains more than the fig-Forth
model. It also contains some additional software:
# Complete CIO interface to ATARI Operating System and DOS
# Support of Graphics/Sound/Joystick routines in O.S.
# Complete support of character string manipulation
# Interface to Disk Handler routines in O.S.
# Screen editor for modification of Forth files
# Text formatter for use with on-line documentation
# Turnkey support to create application programs
!! Chapter 2
! Booting MesaForth
Before you use your MesaForth disk for the first time, you
should make sure it is write-protected so that you can't
accidentally destroy it. It is suggested that you duplicate this
disk and store the original and use it only as a master disk. You
should use another disk when you are running MesaForth. To boot
MesaForth, follow these steps:
# Turn on disk drive and insert MesaForth diskette
# Turn on any other peripherals
# Turn on computer
DOS will boot up first. It will execute the AUTORUN.SYS file
on the system disk. This will load and execute files with
extensions of .IN0, .IN1, .IN2, .IN3, and .IN4 until it finds no
files with these extensions. If you have an Interface Module
(850), you will need the file INTRFACE.IN0 on your system disk.
If you have any other special boot files, they should be loaded
next. Then the MesaForth object file will be loaded and executed
last (FORTH.IN1 on standard system disk). You will then see a
message (fig-FORTH x.x) which announces that you are now in Forth.
At this point, you can enter any existing Forth word or enter a
colon definition.
! Defining system words
When you first boot up your MesaForth, you will have the
minimum subset of Forth words defined. Before you can do anything
else, you will probably need to add the system extensions. These
words are contained in the SYSTEM.4TH file. This file also
contains in screens 4 through 6 the system error messages (you
should usually leave DR0 selected to SYSTEM.4TH). This file
defines some useful extensions to Forth such as character string
manipulation and the :SELECT word. These will be described later.
To load these words, type:
{{{
1 LOAD
}}}
MesaForth will then go out to the disk and load the words from
SYSTEM.4TH.
After it is finished loading, it will type OK. This indicates
that it is finished with the previous command(s) and is ready to
accept new instructions.
! Defining the screen editor words
Now that you have loaded the system words, you can load the
MesaForth editor. To do this, type:
{{{
LOAD-ED
}}}
This will select EDITOR.4TH as DR1 and execute a LOAD for that file.
! Defining the DOS words
Often you will want to perform some standard DOS operations on
your disk. You can do these by loading the DOS words. This can
be done by typing:
{{{
LOAD-DOS
}}}
This will load the words from DOS.4TH. The words available
will allow you to do directories, deletes, renames, locks,
unlocks, and some copying. These words are designed to be
forgotten when you are finished with them. This will release the
memory used by these functions so that you can use it for you
program. To forget DOS, type:
{{{
FORGET DOS
}}}
!! Chapter 3
! MesaForth file format
Some differences have been made in the Forth file structure in
MesaForth. First, the screen size has been modified to 512 bytes.
This change is primarily due to the problem of displaying an
entire Forth screen at one time. Fig-Forth suggests using a
screen size of 1024 bytes (16 lines of 64 characters each). Since
the ATARI line width is at most 40 characters, using 64 character
lines would cause some confusion. In MesaForth, the line size is
32 characters. Each screen still has 16 lines, producing a screen
size of 512 bytes.
Another major change is having Forth run under the ATARI DOS.
Using DOS gives you access to files used by other ATARI
DOS-supported programs. But, running under DOS adds some
additional changes to Forth. First, DOS must be booted before
Forth. DOS requires some memory; you lose this memory for use by
your Forth programs. Also, Forth usually performs random accesses
to screens on disk. But under ATARI DOS, files are normally
accessed sequentially. MesaForth will simulate the random access,
by creating an internal screen list showing the position of each
screen within an ATARI file. After the list has been made (it is
made automatically), then accesses to individual screens will be
very fast (random access).
Note that since MesaForth supports all CIO functions, including
the DOS file accesses, you will normally use Forth files for only
your Forth sources (word definitions). Data files will usually by
normal DOS files.
!! Chapter 4
! Character strings
A useful extension to Forth in MesaForth is the support of
character string operations. Since Forth is stack-oriented for
its numeric operations, it is natural to add character string
words as stack-oriented operations. A special string stack is set
up separate from the numeric stack. It has its own stack pointer
($SP). The size of the string stack is defined by the variable
*$*. The string stack and words are established when you load
SYSTEM.4TH. You can change the size of the stack, or change/add
words by changing SYSTEM.4TH.
Refer to Appendix A for a complete list of the string
operations. For efficiency, no special checks are performed on
the string stack. If you exceed its size, or pop too many
elements off of the string stack, your program will probably
crash. Remember, you can add these checks by modifying the words
in SYSTEM.4TH. The following sections will describe the string
operations provided in MesaForth.
! Stack Manipulaton
{{{
" text" ( -$> $ )
}}}
This operation pushes a quoted text string on top of the string
stack. The string must be terminated by a double quote ("). NOTE
that there "must" be a space between the first quote mark (") and
the first character in the text string. Examples:
{{{
" This is a text string"
" D1:EDITOR.4TH"
}}}
{{{
"" ( -$> $ )
}}}
This word pushes an empty (zero-length) string on top of the
string stack.
{{{
$DROP ( $2 $1 -$> $2 )
}}}
This is like the DROP word, except it drops the top string off
the string stack.
{{{
$DUP ( $1 -$> $1 $1 )
}}}
This is like the DUP word, except that it duplicates the top
string on the stack.
{{{
$FILL ( n c --> ) ( -$> $ )
}}}
This operation, takes the number of characters (n) and the
character (c) off the numeric stack, and produces a string at the
top of the string stack which contains the indicated number of
characters c. Example:
{{{
20 BL $FILL
}}}
This will put a string of 20 blanks on top of the string stack.
{{{
$SWAP ( $1 $2 -$> $2 $1 )
}}}
Just like the SWAP word, except that it swaps the top two strings on the string stack.
! String operations
{{{
$+ ( $1 $2 -$> $1+$2 )
}}}
This operation is similar to the + word; it concatenates the
top string on the stack onto the end of the second string on the
string stack. Example:
{{{
" a" " b" $+
}}}
( this produces "ab" on the string stack )
{{{
$. ( $ -$> )
}}}
This prints the top string on the string stack.
{{{
$< ( --> f ) ( $1 $2 -$> )
}}}
This operation compares the top two string on the string stack.
If $1 is less than $2, then the result (f) will be true(non-zero),
otherwise the result will be false (zero).
{{{
$= ( --> f ) ( $1 $2 -$> )
}}}
Similar to $<, except the result will be true if $1 is equal to $2.
{{{
$COMPARE ( --> n ) ( $1 $2 -$> )
}}}
This word is the internal comparison function. It is called by $<
and $= to perform the actual comparison. It compares the top
two strings on the string stack and returns -1 if $1<$2, 0 if
$1=$2, and 1 if $1>$2.
{{{
$FETCH ( addr len --> ) ( -$> $ )
}}}
This word is used to fetch strings not stored in string
variables. It takes a string starting at the address (addr), and
pushes it on top of the string stack. Its length will len.
{{{
$LEN ( --> n )
}}}
This returns the length of the top string on the string stack.
{{{
$P! ( --> )
}}}
This word resets the string stack pointer (makes the string stack empty).
This is automatically done whenever a warm-restart (or cold-start) is performed.
You can also do this yourself anytime, but be warned that anything that was on the string stack
will be lost.
{{{
$P@ ( --> n )
}}}
This word returns the value of the string stack pointer (which
is pointing to the address of the top string on the string stack).
*NOTE* that you will probably never need to use this word since all
of the string operations can be performed without knowing the
address of the string stack. This word is used in defining the
string operations like $DROP or $SWAP.
{{{
$P2 ( --> n )
}}}
This word returns the address of the second string on the
string stack. *NOTE* that you will probably never need this word.
It is used to define other string operations.
{{{
$STORE ( addr max --> actlen ) ( $ -$> )
}}}
This word is used to store strings into non-string variable
locations. The top string on the string stack is stored into
memory at the address (addr). The maximum string size allowed for
storage is max. This word will return the actual length of the
data stored on top of the numeric stack (actlen).
{{{
$VARIABLE xxx ( len --> )
}}}
Similar to the VARIABLE word, except that the numeric value on
top of the stack indicates how many characters to allocate to the
string variable. This will limit the size of the string which may
be stored in the string variable. But it does not mean that all
strings need to be this size. The actual length is also kept for
each string variable. Example:
{{{
10 VARIABLE NAME ( define 10 character string variable
called NAME )
" Smith" NAME $! ( store 5 character string in NAME )
NAME $VARLEN ( this will return 5, since the actual
length is only 5 )
" Smith, Jonathan" ( this will only store the leftmost 10
characters into NAME, since its max
length is 10 )
}}}
{{{
$VARLEN ( vaddr --> len )
}}}
Returns the actual length of the string variable (vaddr).
{{{
$VARMAX ( vaddr --> max )
}}}
Returns the maximum length of the string variable (vaddr).
!! Chapter 5
! MesaForth Editor
You will be using the MesaForth Editor to create and modify
your Forth source files. This editor is a screen editor; it
allows you to make changes to your source by using the cursor
controls and making changes by typing on the screen without using
special editing commands. The screen editor is similar to the
functions provided by ATARI BASIC or the Assembler/Editor.
To use the editor on a source file, you must first select the
file you wish to edit. This can be done using the $SETDR1 word.
For example:
{{{
" D1:FILE.4TH" $SETDR1 DR1
}}}
This will look for the file FILE.4TH on D1:. It will be used
as DR1. DR1 is then selected as the active file. Now to invoke
the editor, you use a special word:
{{{
EDIT ( screen --> )
}}}
This word invokes the editor on the indicated screen in the
currently active file (DR0 or DR1). The television display will
be cleared and the Forth screen will be displayed. All 16 lines
of the screen will be shown, with a box around it (so that you can
tell what is part of the screen, and what is information shown by
the editor. The bottom of the display will show what special
editor commands are available.
! Standard editing commands:
While you are in the editor, any character you type (except
special control characters) while be entered into the screen at
the current position of the cursor. It will replace whatever was
in that position of the screen. The editor control characters
are:
*arrows*
The arrows (control characters left of the RETURN key) will
move the cursor the appropriate direction in the screen.
*DELETE/BACK-SPACE*
This key will delete the character preceeding the cursor in the
screen.
*SHIFT DELETE/BACK-SPACE*
Holding the shift key down while hitting the DELETE/BACK-SPACE
key will cause the entire line on which the cursor is positioned
to be deleted. All lines below it on the screen will move up to
fill in.
*SHIFT INSERT*
Holding the shift key down while hitting the INSERT key will
insert a blank line at the line on which the cursor is positioned.
All lines (including the line currently holding the cursor) will
move down. Note that the last line in the screen will be moved
outside of the screen. The editor will hold that line for you in
case you accidentally inserted a line. To restore the screen to
its original state, delete the line you just inserted.
*CTRL DELETE/BACK-SPACE*
Holding the ctrl key down while hitting the DELETE/BACK-SPACE
key will delete the character currently under the cursor in the
screen.
*CTRL INSERT*
Holding the ctrl key down while hitting the INSERT key will
cause a space to be inserted at the cursor. All characters after
the cursor (including the character under the cursor) will shift
right one position. The editor will not allow you to shift a
character off the end of the line. You will have to split the
line up if it gets full and you still need to add something to it.
! Special Editing commands
There are some additional editing commands available. To enter
these commands, first hit the ESCAPE key. Then enter one of the
following commands:
*X* (eXit)
This command saves all of the screens that have been edited,
and exits the editor mode, returning you to normal Forth command
mode. You must enter this command before leaving the editor.
Otherwise not all of the screens you have updated will get flushed
to the disk.
*A* (Abort)
This command aborts editing of the current screen. It will
save all of the other screens that have been updated though.
*C* (Copy)
This command allows you to move screens around within your
file. It will ask you for the starting and ending screen numbers
to be moved. It will also you ask you for the number of the first
target screen. Enter each of these numbers, hitting a RETURN
after each.
*E* (Erase)
This command erases the current screen. It fills the entire
screen with blanks.
*S* (Search)
This command is not yet implemented, it would be a search
through the file for a particular string of characters.
< (preceeding screen)
Use this command to move to the preceeding screen in the file.
> (following screen)
Use this command to move to the next screen in the file.
*number* (move directly to a screen)
After hitting the ESCAPE key, enter a number, then a RETURN.
The EDITOR will move directly to that screen.
!! Chapter 6
! ATARI Input/Outputy
MesaForth provides a complete set of Forth extensions
interfacing to the ATARI Operating System. The Input/Output (I/O)
words fall into the following categories:
# Central Input/Output (CIO)
# Disk Handler
# Disk Operating System (DOS)
# Special I/O (sound, graphics, joysticks)
Refer to Appendix A for a complete summary of these functions.
The remainder of this chapter will give a brief description of the
features provided in MesaForth.
! CIO functions
The interface to CIO provides both input and output similar to
what is available in ATARI BASIC. The ATARI Operating System
allows up to 8 files/devices to be operated at a time. They are
identified by individual I/O Control Blocks (IOCB). These IOCB's
are identified by #0, #1, ... #7. MesaForth and the ATARI O.S.
use some of these internally. The IOCB's available for your use
are #0, #3, #4, #5, and #6. These words are defined for you
convenience.
The functions provided are:
| CLOSE | close file/device |
| GET | get character(byte) |
| GETBUF | get buffer from file/device |
| GETREC | get record (terminated by End-Of-Line) |
| JSRCIO | call CIO (assumes IOCB set-up) |
| NOTE | note position in disk file |
| OPEN | open file/device |
| POINT | point to position in disk file |
| PUT | write character(byte) |
| PUTBUF | write buffer to file/device |
| PUTREC | write record (terminated by End-Of-Line) |
| STATUS | return status of file/device |
| XIO | call CIO (like BASIC XIO) |
For a detailed description of OPEN, CLOSE, NOTE, POINT, and XIO
refer to the ATARI BASIC manual. The calling sequence and meaning
of arguments is similar, with the exception of the file name
arguments. The ATARI O.S. requires that file name be terminated
by an EOL. A special string function is provided ($FILE) which
converts the top string on the string stack into a file name, and
returns the address of the name on the top of the numeric stack.
You can use this address in OPEN (or XIO). Then use a $DROP to
drop the file name from the string stack. Example:
{{{
#3 4 0 " D:FILE" $FILE OPEN $DROP
#3 GET
#3 CLOSE
}}}
The above example opens D:FILE and gets the first byte from the
file. The file is then closed. Another word (?DISKERROR) can be
used to abort your program if a disk error occurs.
! Disk Handler
The disk handler words interface to the ATARI O.S. disk handler
routines. They support reading and writing of individual sectors
on a disk (without using the DOS). Two extra words are defined
which will dump sectors from disk, and do a sector by sector copy
of a disk.
! DOS Functions
Some of the DOS functions are supported in MesaForth. You can
delete, lock, rename, and unlock files. You can also do a
directory of your disks. These functions use the string stack for
the name of the file(s). For example:
{{{
" D:*.*" DIR
" D:*.BAK" DELETE
}}}
An additional function (SCRCOPY) can be used to create a copy
of the currently selected file (DR0/DR1).
! Special I/O
Words have been defined to access the sound, graphics, and
joystick functions provided by the ATARI O.S. These words are
similar to the ATARI BASIC commands providing the same features:
| COLOR | selects color |
| DR. | draws line (DRAWTO) |
| GR. | opens screen for graphics (GRAPHICS) |
| LOC. | locates color at point (LOCATE) |
| PL. | plots point (PLOT) |
| POS. | positions graphics cursor (POSITION) |
| SE. | sets color register (SETCOLOR) |
| SO. | sets voice for sound (SOUND) |
| STICK | tests joystick position |
| STRIG | tests joystick trigger |
An additional word (CVTSTK) has been provided to convert the
joystick position values to something more meaningful.
!! Chapter 7
! Miscellaneous Functions
MesaForth provides two additional features useful for creating
turnkey applications in Forth. A text formatter is provided to
support on-line documentation to the screen or to a printer. A
TURNKEY word is provided to save a set of loaded Forth words. A
NEW-ABORT word allows you to chain your own functions into the
warm restart sequence (SYSTEM RESET).
The Text Formatter reads a file generated using the MesaForth
Editor (i.e., a Forth file of screens with no carriage returns).
It looks for a small set of commands starting in column 1 of a line:
| .BREAK | pause on screen (so it can be read) |
| .CENTER text | center text on line |
| .END | end of file |
| .FILL | begin filling of text (right-margin justify) |
| .NOFILL | end filling of text |
| .PAGE | force a start of a new page (clear screen) |
| . | force a blank line |
Use the text formatter to generate instructions for programs
you have written. You call the text formatter (after it is
loaded) by using the FORMAT word. It will display the text on the
screen or print it on a printer. It will stop formatting if the
BREAK key is hit.
To save your own turnkey programs, use the TURNKEY word. It
will save the currently loaded Forth words to a binary file on
disk. Usually you will have a blank disk (formatted, with DOS).
You will use TURNKEY to save your Forth program as AUTORUN.SYS.
TURNKEY sets the fence so that your words cannot be deleted when
you load the new file. Example:
{{{
" D:AUTORUN.SYS" TURNKEY
}}}
A useful feature is to create programs that can be run, but
that can be set so that the user cannot enter Forth to see what
you are doing. This can be done by using the NEW-ABORT word. To
automatically call one of your words when the SYSTEM RESET key is
hit (or when the program is first loaded), define the following
word:
{{{
: START NEW-ABORT yourword ;
}}}
The START word will automatically be executed whenever Forth
restarts (on SYSTEM RESET or initial load). This can be used to
prevent someone from ever getting into Forth. It can also be used
to reset some application specific feature (like the string
stack).
!! Appendix A -- MesaForth Reference
The following reference table describes all of the Forth words available on the Forth system disk. This version of the
Forth Interest Group Forth (figFORTH) is based on Forth 78. The difference (from figFORTH) is the block and screen size (512
bytes). Some of the words are defined in the standard Forth object file, others are defined in Forth source files
on the system disk and can be modified and loaded.
The first column contains the name of the word.
The second column describes the stack operation:
{{{
( input --> output )
( $input -$> $output )
}}}
The normal stack is described with -->, the string stack is described by -$>. The top of the stack is the rightmost
item in a list. The input items reflect the stack before the word is executed. The output items indicate the stack state
after the word is executed. The operands are defined as follows:
| n, n1, ... | 16-bit signed integer numbers |
| d, d1, ... | 32-bit signed integer numbers |
| u | 16-bit unsigned integer number |
| addr | 16-bit address |
| b | 8-bit byte |
| c | 8-bit ATASCII character |
| f | boolean flag (0 is false) |
| iocb | offset of I/O control block (i.e., hex 00, 10, 20, ...) |
The third column indicates the source of the word. The values for this column are:
| fig | fig-Forth word in normal Forth object file |
| ext | MesaForth extensions in Forth object file |
| SYS | in SYSTEM.4TH, words usually needed |
| DISK | in DISK.4TH, disk handler interface |
| DOS | in DOS.4TH, ATARI DOS words |
| EDIT | in EDIT.4TH, Forth screen editor |
| FORM | in FORMAT.4TH, text-formatting words for use in program HELP files |
| TURN | in TURNKEY.4TH, saves current Forth words for turnkey operation |
! Stack Manipulation
| -DUP |( n --> n ? ) |fig|Duplicate only if non-zero|
| >R |( n --> ) |fig|Move top item to "return stack" for temporary storage (use caution)|
| DUP |( n --> n n ) |fig|Duplicate top of stack|
| DROP |( n --> ) |fig|Throw away top of stack|
| OVER |( n1 n2 --> n1 n2 n1 ) |fig|Make copy of second item on top|
| PICK |( nm...n1 --> nm...n1 nm ) |ext|Pick the mth item into the stack and copy it to the top of the stack|
| R> |( --> n ) |fig|Retrieve item from return stack|
| R |( --> n ) |fig|Copy top of return stack onto stack|
| ROT |( n1 n2 n3 --> n2 n3 n1 ) |fig|Rotate third item to top|
| SWAP |( n1 n2 --> n2 n1 ) |fig|Reverse top two stack items|
! Number Bases
| BASE | ( --> addr ) |fig|System variable containing number base.|
| DECIMAL | ( --> ) |fig|Set decimal base.|
| HEX | ( --> ) |fig|Set hexadecimal base.|
! Arithmetic and Logical
|* |( n1 n2 --> prod ) |fig|Multiply.|
|*/ |( n1 n2 n3 --> quot ) |fig|Multiply, then divide (n1*n2/n3), using double-precision intermediate.|
|*/MOD |( n1 n2 n3 --> rem quot ) |fig|Multiply, then divide (n1*n2/n3), using double-precision intermediate.|
|+ |( n1 n2 --> sum ) |fig|Add.|
|- |( n1 n2 --> diff ) |fig|Subtract (n1-n2).|
|/ |( n1 n2 --> quot ) |fig|Divide (n1/n2).|
|/MOD |( n1 n2 --> rem quot ) |fig|Divide (n1/n2), giving both remainder and quotient.|
|1+ |( n --> n+1 ) |fig|Increment number by 1.|
|2+ |( n --> n+2 ) |fig|Increment number by 2.|
|ABS |( n --> absolute ) |fig|Absolute value of n.|
|AND |( n1 n2 --> and ) |fig|Logical AND (bitwise).|
|D+ |( d1 d2 --> sum ) |fig|Add double-precision numbers.|
|D+- |( d1 n --> d2 ) |fig|Apply the sign of n to d1, leaving it as d2.|
|DABS |( d --> absolute ) |fig|Absolute value of double precision number.|
|DMINUS |( d --> -d ) |fig|Change sign of double-precision number.|
|M* |( n1 n2 --> d ) |fig|Multiplies two numbers, producing a double-precision number.|
|M/ |( d n1 --> rem quot ) |fig|Divide double precision number by single precision number, producing single-precision numbers.|
|M/MOD |( ud1 u2 --> u3 ud4 ) |fig|Unsigned divide of double-precision number, producing single precision remainder(u3) and double-precision quotient(ud4).|
|MAX |( n1 n2 --> max ) |fig|Maximum of n1 and n2.|
|MIN |( n1 n2 --> min ) |fig|Minimum of n1 and n2.|
|MINUS |( n --> -n ) |fig|Change sign of number.|
|MOD |( n1 n2 --> rem ) |fig|Modulo (i.e. remainder of n1/n2).|
|OR |( n1 n2 --> or ) |fig|Logical OR (bitwise).|
|U* |( u1 u2 --> ud ) |fig|Unsigned multiplication of two numbers, producing unsigned double-precision number.|
|U/ |( ud u1 --> u2 u3 ) |fig|Unsigned divide of double-precision number by single-precision number, producing unsigned remainder (u2) and quotient (u3)|
|XOR |( n1 n2 --> xor ) |fig|Logical exclusive OR (bitwise).|
! Comparison
|0< |( n --> f ) |fig|True if number is negative.|
|0= |( n --> f ) |fig|True if top number zero (i.e., reverses truth value).|
|< |( n1 n2 --> f ) |fig|True if n1 less than n2.|
|= |( n1 n2 --> f ) |fig|True if n1 equals n2.|
|> |( n1 n2 --> f ) |fig|True if n1 greater than n2.|
! Memory
|! |( n addr --> ) |fig|Store word value at address in memory.|
|+! |( n addr --> ) |fig|Add number to value of word at address in memory.|
|<CMOVE |( from to n --> ) |SYS|Like CMOVE, except bytes moved starting at high address first.|
|? |( addr --> ) |fig|Print numeric value of word at address in memory.|
|@ |( addr --> n ) |fig|Fetch one word from memory at indicated address.|
|BLANKS |( addr u --> ) |fig|Fill u bytes in memory with blanks.|
|C! |( b addr --> ) |fig|Store byte value at address in memory.|
|C@ |( addr --> b ) |fig|Fetch one byte at address from memory.|
|CMOVE |( from to u --> ) |fig|Move u bytes in memory.|
|ERASE |( addr u --> ) |fig|Fill u bytes in memory with zeroes.|
|FILL |( addr u b --> ) |fig|Fill u bytes in memory with a byte value.|
! Control Structures
|BEGIN ...UNTIL |until: ( f --> ) |fig|Loop back to BEGIN until true at UNTIL.|
|BEGIN ...REPEAT |while: ( f --> ) |fig|Loop while true at WHILE. ...WHILE.|
|DO...+LOOP |do: ( end+1 start --> ) +loop: ( n--> ) |fig|Like DO...LOOP, except adds stack value to index at end of loop.|
|DO...LOOP |do: ( end+1 start --> ) |fig|Set up loop, given index range.|
|I |( --> index ) |fig|Place current index value on stack.|
|IF...(true) ...ENDIF |if: ( f --> ) |fig|If top of stack is true (non-zero), execute.|
|IF...(true) ELSE...(false) ...ENDIF |if: ( f --> ) |fig|Like IF...ENDIF, except if false, the ELSE clause is executed.|
|LEAVE |( --> ) |fig|Terminate loop at next LOOP or +LOOP.|
! Terminal Input-Output
|. |( n --> ) |fig|Print number.|
|." |( --> ) |fig|Print message (terminated by ").|
|.R |( n fieldwidth --> ) |fig|Print number, right-justified in field.|
|?TERMINAL |( --> f ) |fig|True if terminal break request present.|
|BELL |( --> ) |SYS|Ring console bell.|
|BL |( --> n ) |fig|Leaves the .ATASCII. value of blank on the stack.|
|COUNT |( addr --> addr+1 u ) |fig|Change length-byte string to TYPE form.|
|CR |( --> ) |fig|Do a carriage return.|
|D. |( d --> ) |fig|Print double-precision number.|
|D.R |( d fieldwidth --> ) |fig|Print double-precision number, right-justified in field.|
|DUMP |( addr u --> ) |SYS|Dump u .bytes. starting at address.|
|EMIT |( c --> ) |fig|Type character c.|
|EXPECT |( addr n --> ) |fig|Read n characters (or until a carriage return) from input to address.|
|KEY |( --> c ) |fig|Read key, put .ATASCII. value on stack.|
|PR-OFF |( --> ) |SYS|Turn the printer off (for terminal I/O).|
|PR-ON |( --> ) |SYS|Turn the printer on (for terminal I/O). All output from TYPE, EMIT, etc. will appear on the screen and the printer. All keyboard input will also be echoed on the printer.|
|SPACE |( --> ) |fig|Type a space.|
|SPACES |( n --> ) |fig|Type n spaces.|
|SPEMIT |( c --> ) |SYS|Allows special characters to be sent to the screen.|
|TYPE |( addr u --> ) |fig|Type string of u characters starting at address.|
|U. |( u --> ) |SYS|Type the unsigned number.|
|WORD |( c --> ) |fig|Read one word from input stream, stopping at character c (usually blank).|
! Input-Output Formatting
|# |( d --> d ) |fig|Convert next digit of double-precision number and add character to output string.|
|#> |( d --> addr u ) |fig|Terminate output string (ready for TYPE).|
|#S |( d --> 0 0 ) |fig|Convert all significant digits of double-precision number to output string.|
|<# |( --> ) |fig|Start output string.|
|HOLD |( c --> ) |fig|Insert .ATASCII. character into output string.|
|NUMBER |( addr - d ) |fig|Convert string at address to double-precision number.|
|SIGN |( n d --> d ) |fig|Insert sign of n into output string.|
! Disk Handling
|B/BUF |( --> n ) |FIG|System constant giving disk block size in bytes|
|B/SCR |( --> n ) |FIG|System constant giving blocks per editing screen|
|BLK |( --> addr ) |FIG|System variable containing current block number|
|BLOCK |( block --> addr ) |FIG|Read disk block to memory address|
|DR0 |( --> ) |FIG|Selects use of .file. 0 for LIST, LOAD, and .EDIT.|
|DR1 |( --> ) |FIG|Selects use of .file. 1 for LIST, LOAD, and .EDIT.|
|EMPTY-BUFFERS |( --> ) |FIG|Erase all buffers|
|FLUSH |( --> ) |FIG|Write all updated buffers to disk|
|INDEX |( from to --> ) |FIG|Lists the first line of the screens indicated|
|LIST |( screen --> ) |FIG|List a disk screen (.512 bytes.)|
|LOAD |( screen --> ) |FIG|Load disk screen (compile or execute)|
|PLIST |( strt end --> ) |SYS|List the screens from strt to end to the printer (and screen)|
|SCR |( --> addr ) |FIG|System variable containing current screen number|
|UPDATE |( --> ) |FIG|Mark last buffer accessed as updated|
! Defining Words
|: xxx f pointer to context vocabulary (searched first)|
|CURRENT |( --> addr ) |FIG|Returns address of pointer to current vocabulary (where new definitions are put)|
|DEFINITIONS |( --> ) |FIG|Sets CURRENT vocabulary to CONTEXT|
|FORTH |( --> ) |FIG|Main Forth vocabulary (execution of FORTH sets CONTEXT vocabulary)|
|VLIST |( --> ) |FIG|Print names of all words in CONTEXT vocabulary|
|VOCABULARY |( --> ) |FIG|Create new vocabulary named xxx|
! Miscellaneous and System
|' xxx |( --> addr ) |FIG|Find address of xxx in dictionary; if used in definition, compile address|
|( |( --> ) |FIG|Begin comment, terminated by right paren on same line; space after (|
|, |( n --> ) |FIG|Compile a number into the dictionary|
|ABORT |( --> ) |FIG|Error termination of operation|
|ADDBLKS |( 0/1 n --> ) |EDIT|Adds n blocks (screens) to the end of DR0(0) or DR1(1)|
|ALLOT |( --> ) |FIG|Leave a gap of n bytes in the dictionary|
|COLD |( --> ) |FIG|Performs a system cold start (erases application program and restarts)|
|EDIT |( n --> ) |EDIT|Enters screen editor for screen n of the current file (DR0/DR1)|
|FORGET xxx |( --> ) |FIG|Forget all definitions back to and including xxx|
|FORMAT |( filespec -$> ) |FORM|Read the file, and format the text on the screen or printer|
|FREE |( --> n ) |SYS|Returns the number of free bytes left in memory|
|HERE |( --> addr ) |FIG|Returns address of next unused byte in the dictionary|
|IN |( --> addr ) |FIG|System variable containing offset into input buffer (used by WORD)|
|NEW-ABORT |( --> ) |SYS|This word is used when compiling another word that is to be executed on a warm-reset (like the SYSTEM RESET key). This word should be the very first word in a colon definition. The remainder of the new word definition will be executed each warm-restart|
|PAD |( --> addr ) |FIG|Returns address of scratch area (usually 68 bytes beyond HERE)|
|SP@ |( n --> ) |FIG|Returns address of top stack item|
! String Functions
|" text" |( -$> $ ) |SYS|Pushes a string constant on top of the str ng stack|
|"" |( -$> $ ) |SYS|Push the empty string on top of the string stack|
|! |( vaddr --> ) ( $ -$> ) |SYS|Store the string at the top of the string stack into the string variable|
|+ |( $1 $2 -$> $1+$2 ) |SYS|Concatenate the top two strings on the string stack|
|+! |( vaddr --> ) ( $ -$> ) |SYS|Concatenate the top string of the string stack onto the end of the string variable|
|. |( $ -$> ) |SYS|Type the string at the top of the string stack|
|< |( --> f ) ( $1 $2 -$> ) |SYS|Compare the top two strings on the string stack and return true if $1 < $2|
|= |( --> f ) ( $1 $2 -$> ) |SYS|Compare the top two strings on the string stack and return true if $1 = $2|
|@ |( vaddr --> ) ( -$> $ ) |SYS|Fetch the string from the string variable, and place it on top of the string stack|
|COMPARE |( --> n ) ( $1 $2 -$> ) |SYS|Compare the top two strings on top of the string stack. Return 1, 0, -1|
|DROP |( $2 $1 -$> $2 ) |SYS|Drop top value from string stack|
|DUP |( $1 -$> $1 $1 ) |SYS|Duplicate the string at the top of the string stack|
|EXTRACT |( vaddr offset char --> offset true ) ( -$> wd ) --> false ) ( -$> ) |SYS| Extracts substrings from a string, starting at the offset within the string looking for the next occurrence of the character. If there is another of the character (or a substring between the offset and the end of the string variable), then true is returned along with the new offset. Otherwise false is returned. This function is useful to extract words from a sentence.|
|FETCH |( addr len --> ) ( -$> $ ) |SYS|Fetch the string starting at the address, with its length as indicated, and place it on the top of the string stack|
|FILL |( n c --> ) ( -$> $ ) |SYS|Create a string at the top of the string stack which has n characters (c)|
|LEN |( --> n ) |SYS|Return length of the string on top of the string stack|
|P! |( --> ) |SYS|Reset string stack pointer|
|P@ |( --> n ) |SYS|Returns value of string stack pointer|
|P2 |( --> n ) |SYS|Return the address of the 2nd string on the string stack (the string below the top string)|
|STORE |( addr max --> actlen ) ( $ -$> ) |SYS|Store the string on top of the string stack at the indicated address. The string will be stored up to the indicated maximum, the actual length of the string stored will be returned on top of the stack|
|SWAP |( $1 $2 -$> $2 $1 ) |SYS|Swap the top two strings on the string stack|
|VARFILL |( vaddr c --> ) |SYS|Fill the string variable with the character (c)|
|VARIABLE xx |( len --> ) |SYS|Creates a string variable with maximum length as indicated|
|VARLEN |( vaddr --> len ) |SYS|Return the length of the string currently in the string variable|
|VARMAX |( vaddr --> max ) |SYS|Return the maximum string length of the string variable|
|*$* |( --> ) |SYS|Variable containing the size of the string stack (512 byte default)|
! ATARI Input/Output(CIO) Functions
|#0 |( --> ) |SYS|Iocb offset for #0|
|#3 |( --> ) |SYS|Iocb offset for #3|
|#4 |( --> ) |SYS|Iocb offset for #4|
|#5 |( --> ) |SYS|Iocb offset for #5|
|#6 |( --> ) |SYS|Iocb offset for #6|
|FILE |( --> addr ) ( $ -$> $+EOL ) |SYS|Makes the string at the top of the string stack into a file name (terminated by an EOL) and returns the starting address on top of the stack. This file name can now be used by CIO functions (OPEN, XIO)|
|(STAT) |( --> n ) |ext|Status of previous CIO call|
|?DISKERROR |( --> ) |ext|Aborts and prints an error message if the previous CIO operation had an error|
|CLOSE |( iocb --> ) |ext|Closes file using iocb|
|GET |( iocb --> b ) |ext|Gets a single byte using the given iocb. Check (STAT) for End-Of-File|
|GETBUF |( iocb addr len --> actlen ) |ext|Performs a get buffer operation using the indicated iocb. The buffer starts at the indicated address and has the indicated length. The transfer will end when the buffer is full, or the end-of-file is reached. The actual length of the data transferred will be returned on the stack|
|GETREC |( iocb addr len --> actlen ) |ext|Same as GETBUF, except the transfer will be terminated at an EOL (End Of Line). This is a get record operation|
|JSRCIO |( iocb cmd --> ) |ext|Performs a call to the Operating System CIO routine. Iocb is the I/O Control block offset and cmd is the CIO command code. The status is stored in (STAT)|
|NOTE |( iocb --> sector disp ) |ext|Notes position in disk file|
|OPEN |( iocb aux1 aux2 nameaddr --> ) |ext|Opens file using iocb, 2 auxilliary bytes (see CIO), and name (terminated by EOL)|
|POINT |( iocb sector disp --> ) |ext|Points to position in disk file|
|PUT |( iocb b --> ) |ext|Output a single byte using the iocb|
|PUTBUF |( iocb addr len --> ) |ext|Outputs the buffer using the iocb. The buffer starts at the indicated address and has the given length.|
|PUTREC |( iocb addr len --> ) |ext|Outputs the record starting at the address, with given length. The record will be terminated by an EOL|
|STATUS |( iocb --> status ) |ext|Performs a status I/O operation using given iocb|
|XIO |( cmd iocb aux1 aux2 addr --> ) |SYS|Sames as BASIC XIO function. Calls CIO|
! ATARI Forth File Functions
|LOAD |( filespec -$> ) |SYS|Open the file as DR1, select DR1, and load the file (starting at screen 1)|
|SETDR0 |( filespec -$> ) |SYS|Open the file as DR0|
|SETDR1 |( filespec -$> ) |SYS|Open the file as DR1|
|LOAD-ED |( --> ) |SYS|Load the screen editor from EDITOR.4TH|
|LOAD-DOS |( --> ) |SYS|Load the DOS utilities from DOS.4TH|
|LOAD-TURN |( --> ) |SYS|Load the turnkey software generator from TURNKEY.4TH|
|TURNKEY |( filespec -$> ) |SYS|Save the current loaded Forth words (including the entire Forth program, but not including the DOS from DOS.SYS)|
! General ATARI Input/Output Functions
|COLOR |( color --> ) |SYS|Selects color to use|
|CVTSTK |( n1 --> n2 ) |SYS|Converts joystick value to a more usable number (0=nothing, 1=up, 2=up-right, 3=right, 4=down-right, 5=down, 6=down-left, 7=left, 8=up-left)|
|DR. |( x y --> ) |SYS|Draws a line from the current position to the X-Y coord.|
|GR. |( mode --> ) |SYS|Opens screen for graphics I/O using iocb #6|
|LOC. |( x y --> value ) |SYS|Sets the cursor to the X-Y coord. and determines the color of that point|
|PL. |( x y --> ) |SYS|Sets the cursor to the X-Y coord. and plots the point|
|POS. |( x y --> ) |SYS|Sets cursor to the X-Y coord.|
|SE. |( reg hue lum --> ) |SYS|Sets a color register to the indicated hue and luminosity|
|SO. |( voice pitch dist vol --> ) |SYS|Sets the voice to the desired pitch, distortion and volume|
|STICK |( port --> ) |SYS|Reads the indicated joystick port (0,1,2,3)|
|STRIG |( port --> f ) |SYS|Reads joystick trigger port, returns true if trigger not pushed|
! ATARI Disk Handler Functions
|COPY |( --> ) |DISK|Makes a bit copy of a disk from drive 1 to drive 2. It reports the status of each read and write on the screen. It will not abort if it should encounter read errors (say from a missing sector on the disk)|
|DMP |( sector --> ) |DISK| Reads a disk sector into a buffer at hex 8000. It reads the sector from drive 2. The sector is then dumped to the screen|
|GETSECTOR |( drive addr sector --> status ) |DISK| Performs a get of the sector on the indicated disk drive (1,2,3,4). The sector (128 bytes) will be read in starting at the address. The sector number (1 to 720) indicates the disk sector. The status of the read will be returned on the stack|
|PUTSECTOR |( drive addr sector --> status )|DISK| Writes a sector to disk. Similar to GETSECTOR|
! ATARI DOS Functions
|DELETE |( filespec -$> ) |DOS| Deletes the file(s). .Warning. there will be no confirmation like normal DOS|
|DIR |( filespec -$> ) |DOS| Lists a directory of the given file(s)|
|FORGET DOS |( --> ) |DOS| Used to forget DOS (after it has been loaded)|
|LOCK |( filespec -$> ) |DOS| Locks the file(s)|
|RENAME |( " Dn:file,file" -$> ) |DOS| Renames file(s)|
|SCRCOPY |( strt end --> ) ( filespec -$> ) |DOS| Creates a new file, copying screens from the current file (DR0/DR1) to the new file|
|UNLOCK |( filespec -$> ) |DOS| Unlocks the file(s)|