Re: One Half of a GS

[dempson@atlantis.actrix.gen.nz (David Empson)]

In article <xu2atRL.ricksyth@delphi.com>,
R FORSYTH  <ricksyth@delphi.com> wrote:
> Some time ago, my ROM 1 IIGS stopped running some of my 8 bit
> programs. (Appleworks 1.2 and a Lucas Films game on a 5 1/4 disk). [snip]
> The Appleworks program  hangs at the "press  spacebar to continue"
> prompt. It just beeps at any key imput. [snip]
> The Lucas game runs but keeps firing like the joystick button was
> being held down 

Both of these are evidence of a stuck pushbutton input from your
joystick (or in the circuitry that detects this signal), or possibly a
fault in the keyboard micro (far less likely).

If button 0 was stuck down, AppleWorks would thing you were pressing
Apple-Space, not Space, and it does distinguish these.

The reason GS/OS programs work fine is that they don't use the
pushbutton input to detect the Apple/Option keys - they use the
keyboard modifier register, which is not influenced by the joystick
inputs.

(The Apple and Option keys are combined with the pushbutton signals
when they are read via $C061 and $C062, and this is how AppleWorks
detects them.)

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand