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1993-06-01
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USEFUL ADDRESSES
No, this isn't a contact service! Here, I will list some addresses in
memory which may be useful to programmers. Unfortunately, I don't know
many, but here they are anyway:
$FF8800 (PSG - You can do 'VU' meters with this one:
poke $FF8800,8 : V1=peek($FF8800)
poke $FF8800,9 : V2=peek($FF8800)
poke $FF8800,10 : V3=peek($FF8800)
You get a value from 0 to 15 depending on the volume of the
particular channel).
$FF8240 colour 0 (Hardware colour registers)
$FF8242 colour 1
$FF8244 colour 2 (Note, each colour is a 'word')
$FF8246 colour 3 (so use DOKE or DEEK)
$FF8248 colour 4
$FF824A colour 5
$FF824C colour 6
$FF824E colour 7
$FF8250 colour 8
$FF8252 colour 9
$FF8254 colour 10
$FF8256 colour 11
$FF8258 colour 12
$FF825A colour 13
$FF825C colour 14
$FF825E colour 15
$FF8203 Produces a rather interesting screen offset thingy.
POKE $FF8203,128 is normal. Try 1,2...
$FF820A You can use this one to either add that professional
touch to a demo, or just to panic the unsuspecting ST
user. POKE $FF820A,254 is normal. 0 flickers the
screen, 1 slowly fades it, 5 angles the screen and
sometimes H-shifts it. Try others...
$FF820F This is the width of the screen. 0 is default, so try
others.
$9F8 Checks to see if the disk is write-protected. (Longword)
? LEEK($9F8) returns -1 for protected, 0 for enabled.
$FB0001 Reads the sample cartridge (Byte)
$4D2 A vertical-blank interrupt vector. You assign music to this
so it plays continuously.
That's all I know, I am afraid. But these ones above may keep you
interested for a while!
Article: BLACK EAGLE 1/6/93