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Re: Writing a patch in ASM

Posted on 2019-08-10, 12:02

Hmm...its kinda working, but with a couple of issues. 1. It only works on my machine in dosbox, because its patching absolute, not relative ? 2. Its not stable, if I exit the game, the OS becomes unstable, it hangs second time around ? 3. I understand 80% of what I pieced together ? If anyone can …

Re: Writing a patch in ASM

Posted on 2019-08-08, 18:47

A generic approach for in-memory patching is, if you tell DOS to load-but-do-not-execute the file , it is in memory and you get the segment address of the program's PSP; from there you can write to whatever locations you want within the program code. Of course, it's a good idea to test your planned …

Re: Writing a patch in ASM

Posted on 2019-08-08, 09:02

That is extremely helpful, thank you sir. What I got so far writing my first ASM program, is a simple 'Hello world'. 1. I need to figure out how to patch in-memory 2. When to patch, the executable needs to decompress itself first, otherwise whats the point. 3. I would probably have to wait for the …

Re: Writing a patch in ASM

Posted on 2019-08-08, 07:25

You provide little information on what you're trying to do (or why a copy of the EXE won't do), but I'm inferring that you'd like to patch the game in-memory and then run it? If so, a good start might be DOS function 4Bh/AL=1 (load but do not execute). My bad, I wasn't too clear about what I wanted …

Writing a patch in ASM *SOLVED*

Posted on 2019-08-06, 10:01

Fella's, I have a game that requires a patch to run properly, there is a bug and I do not want to touch the original exe. After some googling I cant find much information on how to write one in ASM. EDIT: I want to patch the program in memory, its compressed. How do I go about this? (I am new to …

'copy' command overwrites original

Posted on 2019-08-06, 09:44

Can anyone confirm/reproduces this ? I wanted to copy a file in dosbox, instead of pressing shift I hit the enter key resulting in a malformed command. This should result in a syntax error but it does not: (it destroys the file in the process) C:\>copy UNP412B.EXE UNP412B.EXE 1 File(s) copied. C::\> …

Re: Copy protection removal software for DOS games

Posted on 2019-08-02, 10:27

in DOS
You can definitely still send me a PM. I just can't reply. So, go ahead! We are sorry, but you are not authorised to use this feature. You may have just registered here and may need to participate more to be able to use this feature. As soon as this is lifted, I'll drop you a PM. @newrisingsun: I …

Re: Copy Protection & Image Formats

Posted on 2019-08-02, 10:19

Going to do a bit more testing on that game (Ultima IV) and see if I can figure out what is going wrong (eventually.) It results in a "packed file is corrupt" error message. That is the result of Origin applying an older version of Microsoft EXEPACK to AVATAR.EXE. Normally, the ideal solution would …

Re: Preistorik 2 demo

Posted on 2019-08-02, 09:33

It has the expected anti-debugger tactic of prefetch tricks, but for some reason cputype=386_prefetch is not enough to get it running. I'll investigate that later. For now, I've attached the demo's executable with the protection wrapper removed, which DOSBox and other systems will find easier to …

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