Bombuzal doesn't load from TAP

[sp33dy]

Hi,

I've been using a DC2N device to dump tapes, with the plan to help dump tapes for the Tape Preservation group. I've been testing games as I go along and have noticed a couple don't seem to load. I've been testing and comparing against other emulators. The first I'm going to highlight is Bombuzal. The loader shows a scrolling list of details part way through the loading. In CCS64, it shows the colour bars, but doesn't show the text. It just stops. As I state, Vice loads successfully. I've attached the tape here for you. Not sure if you'd be interested in these reports or not.

FYI, the tape is only 97% recognised in TapClean and doesn't clean up any further. However, this wouldn't explain why it works in Vice and freezes in CCS64.

Thanks and kind regards

Sp33dy

[ingehp]

The TAP is working 100%. The problem here is a little bug in the IRQ-Emulation!

I've experienced this on several other occations as well. It seems like under certain circumstances, the IRQ just starts over again and again.

Technically speaking, the IRQ always ends with a RTI. When this command is executed, the CPU simply finishes the interrupt and returns to the program code that was running. However, due to a malfunction in CCS64's emulation, the interrupt triggers immediately, and the CPU starts to execute the interrupt code instead of the normal code which should be run inbetween. The result is that CCS64 executes only the IRQ-code, and not the rest.

It seems like there are certain conditions that leads up to this kind of lock-up, but I haven't found out what exactly happens before this sets in. It looks to me like CCS64 forgets to clear a flag somewhere, or mis-interprets some IO-registers (and that's strange indeed, since the emulation otherwise is great), believing that the IRQ is due to start immediately after it ends.

Regards,
Inge

[Stuart Toomer]

This problem should be fixed in CCS64 V3.9, which has been released recently. Plesae re-download and try again.