CMDS.TXT

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pdpapl video processor commands
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=== 0: NOP ===

Do nothing.

Format:	0

=== 1: MOV ===

Move to the X,Y pixel position on the terminal screen.

Format:	1XxxYyy
Xxx:	Target column as a three-crumb unsigned integer.
Yyy:	Target row as a three-crumb unsigned integer.

=== 2: DRW ===

Draw a sequence of pixels to the terminal starting at the
current cursor position.

NOTE:	Take caution to avoid going past column 39; this will cause
	a newline to occur and (amongst other things) double-width
	settings will be reset.

Format:	2NnPpp...
Nn:	The number of following crumbs (Ppp...) containing pixel data
	as a two-crumb unsigned integer.
Ppp...:	A stream of bits, where 1 represents a pixel to be drawn,
	and 0 represents a pixel to be erased.

=== 3: SUB ===

Initiate a subcommand.

Format:	3S
S:	Subcommand ID, as signified below:

0  END	Wait and do nothing till the Line Time Clock signals the
	next frame is to begin processing.
1  CLR	Clear the screen to the background colour.
2  INV	Toggle reverse video.
3  EOF	Quit.