How do I write programs for the Apple Graphics Tablet?
The Apple Graphics Tablet I know of is rather large and heavy; its pen is attached to it with a (too short) cable; it makes funny sounds that change when the pen is moved in/out the reach of of the tablet. A long time ago I patched a few programs to make use of this tablet. To make it clear in the first place – I don’t have these patched versions available anymore :-(. But I found a listing from which I can tell you this: To detect the interface card, I looped over all slots to check in its firmware for $B0 at location $Cx01 and $20 at location $Cx09 x being the slot number. I never found this ‘signature’ in any other firmware. To check for the pen position one has to poll the tablet (again x being the slot number): LDA $CFFF ; switch off all extension ROMS LDA $Cx00 ; switch on the extension ROM of the tablet LDA #$Cx STA $07F8 ; initialize some hidden text screen data area for the tablet firmware JSR $CBB9 ; call well known location 😉 in tablet firmware When the pen is in reach of
