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First post, by exofreeze

Posted on 
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Trying to get Rasterscan (an older pc booter era title) running in dosbox. Using 0.74.

When I run the game nothing appears to happen. In the debug version I see:
CPU:Illegal/Unhandled opcode FFDB
CPU:Illegal/Unhandled Interrupt Called 6

This repeatedly scrolls by.

I have tried changing the core from auto to normal.

I have also tried several different cputypes (386, 386_prefetch, 386_slow)

I have also tried turning off all extended/upper memory options. So far, none have seemed to help.

I also tried the 8/12/12 svn build.

Reply 1 of 2, by ripsaw8080

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FYI, those repeated debug messages are indicative of a crash where the CPU has left intended execution paths and is executing nonsense instructions.

The DOS conversion of the game has a nasty bug that overwrites the stack when loading the disk image into memory. Even if it didn't crash in some versions of DOS, it would likely overwrite some part of the game code or data with stack values. Very bad... and you can't just boot the floppy image (GAME.DAT) directly because it must be modified in memory by the driver program.

The driver program was created by Mok, who made a number of such conversions back in the late 90's and early 00's. I've attached a modified version of the program that cares for the stack.

Attachments

  • Filename
    RSFIX.ZIP
    File size
    278 Bytes
    Downloads
    150 downloads
    File license
    Fair use/fair dealing exception
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