akbasic/docs/11-verb-reference.md

11. Verb reference

Every statement, alphabetically. This list is generated from the interpreter's own dispatch table, so it cannot drift out of step with what the program actually accepts.

A verb marked Refused parses and then reports why it cannot run — see Chapter 13 for the reasoning in each case.

Verb	Form	What it does
APPEND	APPEND n, "name"	Open a file on channel n for writing at its end.
AUTO	AUTO n	Number lines automatically in steps of n. AUTO 0 turns it off.
BACKUP	BACKUP	Refused. Duplicates one disk onto another; there are no disks.
BEGIN	IF c THEN BEGIN	Start a block that runs to BEND, so an IF can span lines.
BEND	BEND	End a BEGIN block.
BLOAD	BLOAD "name", addr, len	Read a file into memory. The length is required.
BOOT	BOOT	Refused. Loads and runs a boot sector; there is none.
BOX	BOX src, x1, y1, x2, y2 [,angle]	Outline a rectangle, optionally rotated.
BSAVE	BSAVE "name", from, to	Write a range of memory to a file.
CATALOG	CATALOG	Refused. The other name for DIRECTORY.
CHAR	CHAR col, x, y, "text"	Put text at a character cell. Needs a sink with a cursor.
CIRCLE	CIRCLE src, x, y, rx, ry [,...]	Draw an ellipse, arc or polygon.
CLR	CLR	Drop every variable and function, keeping the program.
COLLECT	COLLECT	Refused. Validates a disk's block allocation map.
COLLISION	COLLISION 1 [,target]	Call a subroutine when sprites collide. No target disarms it.
COLOR	COLOR src, index	Bind a colour source to a palette index, 1 to 16.
CONCAT	CONCAT "a", "b"	Append file a to file b.
CONT	CONT	Resume a program stopped by STOP.
COPY	COPY "a", "b"	Copy file a to file b.
DATA	DATA v [, ...]	Declare values for READ. Collected before the program runs.
DCLEAR	DCLEAR	Close every open channel. The half of a drive reset that means something.
DCLOSE	DCLOSE [n]	Close channel n, or every channel.
DEF	DEF NAME(args) = expr	Define a function. Multi-line definitions end in RETURN.
DELETE	DELETE [n][-n]	Delete lines, with the same range forms as LIST.
DIM	DIM A#(n [,...])	Make an array. Subscripts start at zero; n is the count.
DIRECTORY	DIRECTORY	Refused. Needs a directory-reading wrapper that does not exist yet.
DLOAD	DLOAD "name"	Load a program from a file.
DO	`DO [WHILE c	UNTIL c]`
DOPEN	DOPEN n, "name" [,W]	Open a file on channel n. W opens it for writing.
DRAW	DRAW src, x, y [TO x, y ...]	Plot a point or draw a polyline.
DSAVE	DSAVE "name"	Save the program to a file.
DVERIFY	DVERIFY "name"	The other name for VERIFY.
END	END	Stop the program. Does not arm CONT.
ENVELOPE	ENVELOPE n, a, d, s, r	Define one of PLAY's ten envelope presets.
EXIT	EXIT	Leave the innermost FOR or DO loop.
FETCH	FETCH count, from, to	Copy bytes. The same as STASH; there is no expansion RAM.
FILTER	FILTER ...	Refused. There is no filter stage in the audio backend.
FOR	FOR V = a TO b [STEP c]	Start a counted loop, ended by NEXT.
GET	GET V	Take a keystroke if one is waiting, without stopping.
GETKEY	GETKEY V	Wait for a keystroke, holding the program but not the host.
GOSUB	GOSUB line	Call a subroutine, returning on RETURN.
GOTO	GOTO line	Jump to a line or a label.
GRAPHIC	`GRAPHIC mode	CLR`
GSHAPE	GSHAPE A$, x, y	Stamp a region saved by SSHAPE.
HEADER	HEADER "name"	Refused. Formats a disk.
HELP	HELP	Re-list the line the last error happened on.
IF	IF c THEN s [ELSE s]	Branch. Everything after THEN belongs to the condition.
INPUT	INPUT ["prompt"] V	Read a line from the user.
INPUT#	INPUT #n, V	Read a line from a channel.
KEY	KEY [n, "text"]	Define a function-key macro, or list them all.
LABEL	LABEL NAME	Mark this line with a name any branch can use.
LET	LET V = expr	Assign. Optional; assignment needs no verb.
LIST	LIST [n][-n]	List the program, or part of it.
LOAD	LOAD "name"	The other name for DLOAD.
LOCATE	LOCATE x, y	Move the pixel cursor.
LOOP	`LOOP [WHILE c	UNTIL c]`
MOVSPR	MOVSPR n, ...	Move a sprite. Four forms; see Chapter 8.
NEW	NEW	Erase the program and every variable.
NEXT	NEXT V	End a FOR loop and advance its counter.
ON	`ON e GOTO	GOSUB t [,...]`
PAINT	PAINT src, x, y	Flood-fill the region containing a point.
PLAY	PLAY "notes"	Queue notes. Does not block.
POKE	POKE addr, byte	Write a byte to a real address.
PRINT	PRINT [expr]	Print a value and a newline.
PRINT#	PRINT #n, expr	Write a line to a channel.
PUDEF	PUDEF "chars"	Redefine what PRINT USING pads and punctuates with.
QUIT	QUIT	End the interpreter.
READ	READ V [,...]	Fill variables from the next DATA items.
RECORD	RECORD n, r [,pos]	Position a channel at record r. Records are lines.
RENAME	RENAME "a", "b"	Rename a file.
RENUMBER	RENUMBER [start [,step [,from]]]	Renumber lines, rewriting every branch to match.
RESTORE	RESTORE [line]	Reset the READ cursor, optionally to a line.
RESUME	`RESUME [NEXT	line]`
RETURN	RETURN [expr]	Return from a GOSUB or a multi-line DEF.
RUN	RUN [line]	Run the program, optionally from a line.
SAVE	SAVE "name"	The other name for DSAVE.
SCALE	SCALE on [,xmax, ymax]	Turn user coordinates on or off.
SCNCLR	SCNCLR	Clear the text screen.
SCRATCH	SCRATCH "name"	Delete a file.
SLEEP	SLEEP seconds	Pause. Holds the program, not the host.
SOUND	SOUND v, freq, dur [,...]	Play a tone on a voice. Does not block.
SPRCOLOR	SPRCOLOR [c1] [,c2]	Set the two shared multicolour registers.
SPRITE	SPRITE n [,on] [,col] [,...]	Configure a sprite. Omitted arguments are left alone.
SPRSAV	SPRSAV source, n	Give sprite n a picture. Three source forms; see Chapter 8.
SSHAPE	SSHAPE A$, x1, y1 [,x2, y2]	Save a screen region; A$ receives a handle.
STASH	STASH count, from, to	Copy bytes. The same as FETCH.
STOP	STOP	Stop the program; CONT resumes it.
SWAP	SWAP A, B	Exchange two variables of the same type.
SYS	SYS addr	Refused. There is no 6502 and no ROM to call.
TEMPO	TEMPO n	How fast PLAY releases its queue.
TRAP	TRAP [target]	Send errors to a handler. No target disarms it.
TROFF	TROFF	Turn line tracing off.
TRON	TRON	Turn line tracing on; each line prints its number in brackets.
VERIFY	VERIFY "name"	Compare the program in memory against a file.
VOL	VOL n	Set the overall volume, 0 to 15.
WAIT	WAIT addr, mask [,xor]	Poll a byte until it matches. Holds the program.
WIDTH	`WIDTH 1	2`
WINDOW	WINDOW l, t, r, b [,clear]	Constrain the text area. Needs a sink with a grid.

Words that are not verbs

AND, ELSE, NOT, OR, REM, STEP, THEN, TO, UNTIL, USING and WHILE are reserved, but none of them is a statement on its own — each is consumed by the verb it belongs to.

Deliberately absent

BANK, FAST, MONITOR and SPRDEF have no table entry at all. The first three are incompatible with a modern machine — there is no bank switching, no CPU speed to control, and no machine-language monitor to drop into. SPRDEF is an interactive full-screen editor rather than a programmable verb.