CRT chess game crashing

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cercamon
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CRT chess game crashing

Post by cercamon »

Taking the cue from another thread here on Denial, a few days ago I decided to try Sargon II chess game for the Vic.
I have found the cartridge image in TOSEC archive, CRT folder. It starts on VICE (under Linux) but always crashes with jammmed CPU at $c005 everytime the program has to make its move.

The file is a CRT image and its filename is something like Sargon_II_blah_blah.a0. I've also tried loading the cartridge image at $A000 or as a standard cartridge but the result is always the CPU jam. Any advice?

TIA
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cercamon
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Re: CRT chess game crashing

Post by cercamon »

Update: I have found another "copy" of the game online (a .prg to be mounted as a cartridge) and this worked right away.
I am still curious about the .a0 file, that doesn't work.

Also I tested the game and found it very strong at level 0... It's incredible what this sw can do with just 8KB cartridge/RAM in total.
It might be interesting to get the source code or try to reverse-engineer this.
wimoos
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Re: CRT chess game crashing

Post by wimoos »

Not many people know this, but Sargon II holds an easter egg: if you press CTRL-Shift-C= in the startup screen, a copyright message is displayed. Maybe other cartridge have a similar easter egg, I don't know.

I figured this out over 30 years ago when I did some reverse engineering of the cartridge.

I'm not sure what regenerating the complete source code might bring you. A lot of effort before you maybe find some algorithms. And then what ?

In my VIC I have an R65C02 CPU. Optimizing the code for this processor might speed up the play a little, but then hey, running it in VICE at warp speed is less effort and more success. So...

Regards,

Wim.
VICE; selfwritten 65asmgen; tasm; maintainer of WimBasic
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cercamon
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Re: CRT chess game crashing

Post by cercamon »

Thanks for the easter egg. Didn't know about it.
I agree with you that reverse-engineering the machine code would be too much trouble and would take a lot of time to find the algorithm used in the gameplay.

I often wonder, since these games are now pretty old and, some may say, obsolete, if there's the chance that the software house or the programmer himself would release the code or information about the "making of". It would be very interesting to me and it would have an historical value, I think.
It happened some time ago with Prince of Persia, the author Jordan Mechner released a little book to explain his inspiration and also his technical notes and the source code https://github.com/jmechner/Prince-of-Persia-Apple-II. It happened also with Bob Pape recently http://bizzley.com/.

My interest with Sargon II spawns from the rumours that Mikhail Botvinnik, GM and former Chess World Champion did contribute to the algorithm and so the play strength of the game is partly due to his contribution. So I wondered what was the algorithm used.
TNT
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Re: CRT chess game crashing

Post by TNT »

Have you seen this?
http://web.archive.org/web/200706141143 ... argon.html

This post will give you a starting point if you decide to start disassembling Sargon II.
http://sleepingelephant.com/ipw-web/bul ... 329#p80329
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cercamon
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Re: CRT chess game crashing

Post by cercamon »

This is just great! Thanks TNT. It's exactly what I was looking for. Thank you so much. A great reading.
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