ZX Spectrum Screen Driver
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The Spectrum Screen Driver has finally moved off the laurels of rst 16.

The new screen driver is still fairly minimal but it does feature 64
column text and 32 column text (switchable) and can be easily extended.

Here are the byte sequences for it:


1,64	  - Switch to 64 column mode
1,32	  - Switch to 32 column mode

8,9,10,11 - Move in x and y as you would expect
12	  - Form feed - clears the screen and moves print posn to 0,0
13	  - Carriage return - advances y and sets x to 0

22,y,x	  - Move to position y,x on the screen (0<=y<=23, 0<=x<=63)
	    NB. y and x are displaced by 32 eg to move the print position
	    to (0,0) use 22,32,32

All these commands can be embedded in strings using either octal or
hexadecimal representation.

The screen now scrolls when line 24 is "hit", the routine used is in the
48k ROM.

dom
19/3/2000






