King's Quest floppy disk does not boot properly

[ct6502]

King's Quest (woz-a-day collection).zip

Uncompress zip, insert King's Quest disk A into floppy, then boot. Hangs at "Please wait..." screen. Debugger shows that it's oscillating between PC=0xFFFF and 0x0.

Debugging shows that it might be messing up in the following block:

Perhaps the LDA $C08C,X is doing something wrong with the memory softswitches?

[ct6502]

If I put a breakpoint at $FF26, the accumulator contains $C0, which was presumably just read from the woz disk image. If I change the accumulator to $C9, then the game boots properly. This might be some sort of copy protection which my emulator fails to emulate. I tried this in Virtual II - it has $C9 when it hits $FF26, and has no problem booting the game.

[ct6502]

Space Quest has the exact same issue - break at $FF26, change the accumulator to $C9, then continue. https://archive.org/download/wozaday_Space_Quest

[univta0001]

The recent fixes in WOZ handling, somehow allow the King Quest and Space Quest to boot and reach the main screen

[ct6502]

Fixed as part of fixes for #81