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Crypt of the Undead atx images wanted

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Hi guys,

 

Just a note to say that my atx does work from disk (I thought it did but just rewrote it to check) but not Altirra. Not sure if this was mentioned earlier. From what I remember the disk was rough, but as it loaded it all seemed fine (with nothing to compare it to).

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While catching up with latest a8preservation torrent, this title crossed my path again. I again stumbled over its requirement for BASIC Rev. A which I completely had forgotten and overlooked.

 

While analysing the loader program "GO", a USR call right into DOS caught my eye:

 

grafik.thumb.png.19af162bac99b91b8f5b70b1b21b534f.png

 

Line 10000 in text form because AA formats the graphics very small:

10000 POKE 10,35:POKE 11,242:POKE 12,136:POKE 13,7:POKE 1804,48:POKE 1805,18:TRAP 10100:X=USR(1928)

It jumps right into the middle of DOS's sector read routine and there onto the address part of an STA command which does not make any sense:

 

grafik.png.84a8f29b91bbf71083ef75e0f4d83d38.png

 

This sparked some interest on my side and eventually to the idea that $788 might make sense for Atari DOS 1.0 a.k.a. "Disk File Manager".

Some browsing of Atarimania revealed a DOS 1 Reference Manual which contains this information:

 

grafik.thumb.png.2751afca245ab6d6dd392ff089653890.png

If you compare the preceding POKE commands to the ones in the source of the loader, you will also find a lot of similarities. ;)

 

Case closed:

Marc Benioff wrote the game on/for Atari's DOS 1.0, but Epyx released it with DOS 2.0S and it works only by accident because the falsely called routine only reads the last sector read again into DOS' sector buffer.

 

 

Edited by DjayBee
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On 11/30/2020 at 2:22 PM, DjayBee said:

While catching up with latest a8preservation torrent, this title crossed my path again. I again stumbled over its requirement for BASIC Rev. A which I completely had forgotten and overlooked.

 

While analysing the loader program "GO", a USR call right into DOS caught my eye:

 

grafik.thumb.png.19af162bac99b91b8f5b70b1b21b534f.png

 

Line 10000 in text form because AA formats the graphics very small:

10000 POKE 10,35:POKE 11,242:POKE 12,136:POKE 13,7:POKE 1804,48:POKE 1805,18:TRAP 10100:X=USR(1928)

It jumps right into the middle of DOS's sector read routine and there onto the address part of an STA command which does not make any sense:

 

grafik.png.84a8f29b91bbf71083ef75e0f4d83d38.png

 

This sparked some interest on my side and eventually to the idea that $788 might make sense for Atari DOS 1.0 a.k.a. "Disk File Manager".

Some browsing of Atarimania revealed a DOS 1 Reference Manual which contains this information:

 

grafik.thumb.png.2751afca245ab6d6dd392ff089653890.png

If you compare the preceding POKE commands to the ones in the source of the loader, you will also find a lot of similarities. ;)

 

Case closed:

Marc Benioff wrote the game on/for Atari's DOS 1.0, but Epyx released it with DOS 2.0S and it works only by accident because the falsely called routine only reads the last sector read again into DOS' sector buffer.

 

 

nice catch, this might be something to search out in a few more titles... might be a few more like this :)

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