Author: jason (dnvrdslgw13poold17.dnvr.uswest.net)
Date: 10-01-2002 02:26
if you don't want mouse movement to effect your rasters at all then you can disable the keyboard interupt of the MFP. Of course, this means that you will not be able to use the BIOS routes to read the keyboard, but you can always check $fffffc02.b periodically to see if a key has been pressed (most demo code uses this sloppy technique). Example: Space bar=$39, when you hit space, $fffffc02.b=$39.
To disable the keyboard/midi interupt ($118.l):
bclr.b #6,$fffffa09.w
To enable the keyboard/midi interupt:
bset.b #6,$fffffa09.w
That will certainly keep the rasters from being disturbed by the mouse. If you don't want to do that you can write your own ACIA routine, but keep in mind that the MFP vector is shared by both MIDI and Keyboard, you have to poll the ACIAs to figure out who triggered the interupt!
By the way, make sure you disable TimerC if you dont need it, which I'm pretty confident you dont. It will interfere with rasters too. To do that: bclr.b #5,$fffffa09.w
Also, when the blitter and the 68K "share" the bus (the blitter must be set to "share" mode to do this) then they take turns using 64 cycles each. I really don't recommend using the blitter though. Show me code that uses the blitter and I can show you faster code that uses just the 68000.
-jason
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