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Posted By

Csabo
on 2024-05-28
08:49:09
 Ufo Vadasz clean crack

I've added a clean PRG version for Ufo Vadász to the site, which also fixes a minor bug. Thanks to Rüdiger for finding this issue in the first place, and to Lacus for verifying the cassette again.

I've concluded that the game has an odd bug, but the only known crack (the CSM version) happens to work. It's an odd issue, and might be one of those things that coders (or gamers) might be interested in, so I added a little write-up.

Posted By

gerliczer
on 2024-05-28
09:44:54
 Re: Ufo Vadasz clean crack

That $DC04 address looks like a C64 artefact. Like the author borrowed some code from a C64 programme, rewrote it to the C16 and since it worked he left that error there. grin

Posted By

Gaia
on 2024-05-29
17:27:14
 Re: Ufo Vadasz clean crack

That's cool, well spotted! I wonder which game he borrowed the code from...?

Posted By

Csabo
on 2024-05-29
17:40:28
 Re: Ufo Vadasz clean crack

That's neat idea, but $DC04 on C64 is apparently a timer register. I think it's pretty unlikely that that there's any code that uses that timer plus the raster counter. Additionally, the programmer seems pretty knowledgeable about the Plus/4. He handles $FF1D in many other places, this is the only one that's odd, which is my bet is still on some kind of data corruption.

Well, it's fun to speculate happy

Posted By

Gaia
on 2024-05-30
16:55:48
 Re: Ufo Vadasz clean crack

It could have been used as a random number generator



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