Mephisto Chess Genius

Discussion of anything and everything relating to chess playing software and machines.

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towforce
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Re: Mephisto Chess Genius

Post by towforce »

If permission could be obtained, would it be feasible to decompile then recompile the code?
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Ras
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Re: Mephisto Chess Genius

Post by Ras »

towforce wrote: Mon Jan 13, 2025 8:31 pmIf permission could be obtained, would it be feasible to decompile then recompile the code?
There is nothing to decompile because it wasn't compiled in the first place. It's handwritten assembly, so an assembler was used. That's a stage after the compiler, so there is no original C source that you could try to recover. Even worse, the structure of handwritten assembly often doesn't map well to a higher level language because you can do all sorts of dirty tricks in assembly to get the last drop of performance.

I think Lang ported the whole engine to C at some later point.
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Jjaw
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Re: Mephisto Chess Genius

Post by Jjaw »

As close as you're going to get is 3 of Langs championship Mephisto modules as UCI in Rebels Gideon Pro UCI package. You can find it on the web.
Last edited by Jjaw on Mon Jan 13, 2025 11:26 pm, edited 1 time in total.
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towforce
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Re: Mephisto Chess Genius

Post by towforce »

Ras wrote: Mon Jan 13, 2025 8:47 pm
towforce wrote: Mon Jan 13, 2025 8:31 pmIf permission could be obtained, would it be feasible to decompile then recompile the code?
There is nothing to decompile because it wasn't compiled in the first place. It's handwritten assembly, so an assembler was used. That's a stage after the compiler, so there is no original C source that you could try to recover. Even worse, the structure of handwritten assembly often doesn't map well to a higher level language because you can do all sorts of dirty tricks in assembly to get the last drop of performance.

Yes - very good point.

It is possible to convert assembly to a high level languages - e.g. link.

However, some caveats:

1. Because it's an AI tool, it's probably not as good as a hand-written (reverse) compiler

2. Even if it did get everything right, there's still a strong possibility that it will make some moves differently at the same stage in its calculations because different parts of the code may not be quite so well tuned to each other

Probably best to make a case to Mr Lang to release his own port to C to open source.
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Re: Mephisto Chess Genius

Post by Werewolf »

towforce wrote: Mon Jan 13, 2025 11:22 pm
Probably best to make a case to Mr Lang to release his own port to C to open source.
^ this
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Re: Mephisto Chess Genius

Post by Engin »

Paloma wrote: Mon Jan 13, 2025 1:46 pm
Engin wrote: Mon Jan 13, 2025 11:49 am
Werewolf wrote: Mon Jan 13, 2025 10:46 am If the source code was released it would be possible to convert it to a 64 bit UCI. You could write to Mr. Lang and ask?
i ask him in Santiago why is it only 32bit and if its possible to port it to 64 bit, but he answered that takes to much work to rewrite it for 64 bit.

so i need a tool for old 32 bits EXE files to run that on 64 bit windows, i had got it run with Virtualbox on 32 bit windows, but i want run it on 64 bit.
Stefan Meyer-Kahlen was also in Santiago, right?
Has anyone there heard if there is still a Shredder 14?
Or is the Shredder Project dead?
No, Stefan was not in Santiago, the Shredder engine is still available.
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Re: Mephisto Chess Genius

Post by Engin »

Ras wrote: Mon Jan 13, 2025 6:00 pm
Engin wrote: Mon Jan 13, 2025 12:59 pmA simple tool should be enough that runs 32bit EXE file in 64bit OS systems.
64 bit Windows can run 32 bit applications just fine. What 64 bit Windows cannot do, is running 16 bit code - but 32 bit Windows can do that.

Specifically for ChessGenius, the earlier versions were for MS-DOS, so 16 bit code. What has happened is that Lang slapped a Windows GUI on the existing DOS-engine, and this GUI is in fact 32 bit as per the executable's header, but the engine underneath (GENG7.EXE) is still 16 bit code. What's more, it's hand-coded assembly. Porting that would indeed be a lot of work, so it's not going to happen for an old engine version.

However, ChessGenius 7.2 does run under 64 bit Linux with Wine, at least I was able to install it, start it, and play some moves in the demo version.
why it is working on linux but not on windows 64 bit ?
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Re: Mephisto Chess Genius

Post by Engin »

Ras wrote: Mon Jan 13, 2025 8:47 pm
towforce wrote: Mon Jan 13, 2025 8:31 pmIf permission could be obtained, would it be feasible to decompile then recompile the code?
There is nothing to decompile because it wasn't compiled in the first place. It's handwritten assembly, so an assembler was used. That's a stage after the compiler, so there is no original C source that you could try to recover. Even worse, the structure of handwritten assembly often doesn't map well to a higher level language because you can do all sorts of dirty tricks in assembly to get the last drop of performance.

I think Lang ported the whole engine to C at some later point.
if he has ported to C then it should more easier to compile it for 64 bit i guess or ?
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Re: Mephisto Chess Genius

Post by Engin »

towforce wrote: Mon Jan 13, 2025 11:22 pm
Ras wrote: Mon Jan 13, 2025 8:47 pm
towforce wrote: Mon Jan 13, 2025 8:31 pmIf permission could be obtained, would it be feasible to decompile then recompile the code?
There is nothing to decompile because it wasn't compiled in the first place. It's handwritten assembly, so an assembler was used. That's a stage after the compiler, so there is no original C source that you could try to recover. Even worse, the structure of handwritten assembly often doesn't map well to a higher level language because you can do all sorts of dirty tricks in assembly to get the last drop of performance.

Yes - very good point.

It is possible to convert assembly to a high level languages - e.g. link.

However, some caveats:

1. Because it's an AI tool, it's probably not as good as a hand-written (reverse) compiler

2. Even if it did get everything right, there's still a strong possibility that it will make some moves differently at the same stage in its calculations because different parts of the code may not be quite so well tuned to each other

Probably best to make a case to Mr Lang to release his own port to C to open source.
That i hope too, then the C code can be easy compile to 64 bit
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mclane
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Re: Mephisto Chess Genius

Post by mclane »

I do not think shredder is continued. There is no new shredder version in the last years.
In opposite to new colossus versions.

Richard lang , like Ed Schroeder, „retired“ from commercial computer chess .
His motorola 680x0 versions were assembler. Later engines were imo not assembler but C.
The motorola versions were the foundation of his success with Hegener and Glaser and Ossi Weiner.

Although Richard Lang did work before HG for David Levy.
His 8bit engine was sold as Cyrus and Cyrus II on many machines. Then dedicated chess computers for hanimex and cxg and other companies. After 1984 came the Hegener and Glaser age.
With many championship titles such as in amsterdam, dallas, rome, almeria, portorose, vancouver…

Richard was in Santiago de Compostela.

Almost any participant there made selfies with „King Richard“.
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Here we have a fairy tale of the day after tomorrow....