Re: Using debug.exe and experimenting with x86 instructions in DOSBox

Posted on 2020-02-14, 15:08

by

by llm

in DOSBox General

in DOSBox General

A question: how does the CPU handle far calls in realmode? When e.g. an .exe file contains say "call far abdc:1234" does that mean the program will literally jump to that exact spot or is that what relocation items are for? every loading segment related data/code (jumps,call,offset,etc.) are …

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Re: Using debug.exe and experimenting with x86 instructions in DOSBox

Posted on 2020-02-14, 12:15

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by llm

in DOSBox General

in DOSBox General

Does the DOSBox debugger allow you to feed it a few instructions and execute them? no but as stated you can use a Visual Studio Debugger + simple x86 C/C++ Project for that (if VStudio is around) int main() { __asm { mov al, 2 mov dx,0xD007 add dx, al } return 0; } but maybe debug.exe fits already …

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Re: Using debug.exe and experimenting with x86 instructions in DOSBox

Posted on 2020-02-14, 05:14

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by llm

in DOSBox General

in DOSBox General

Looking for a way to quickly test the effect of x86 instructions 1. you can use visual studio with x86 inline assembler - works as long as segmented memory access or io ports access is not relevant to you, all 8/16/32bit opcodes still working 2. use Turbo/Borland C/C++ in Dosbox with Inline- …

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Re: Ways to dump memory to a file->

Posted on 2020-02-09, 18:58

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by llm

in DOSBox General

in DOSBox General

@Peter Swinkels reverse engineering is one of the stronges topics in software development - its very complicated and time consuming - you can spend month only on Alley Cats analysis (btw: someone does that already: https://github.com/gabonator/Work-in-progress/tree/master/DosGames/AlleyCat) 1. …

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Re: repne/repnz movsw: Invalid instruction prefix mystery

Posted on 2019-08-21, 07:52

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by llm

in DOSBox General

in DOSBox General

jmars seems to be right: https://c9x.me/x86/html/file_module_x86_id_279.html

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Re: trouble with a program: cup386

Posted on 2019-08-20, 11:12

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by llm

in DOSBox General

in DOSBox General

normal core?

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Re: repne/repnz movsw: Invalid instruction prefix mystery

Posted on 2019-08-20, 11:12

by

by llm

in DOSBox General

in DOSBox General

thx for the help

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Re: repne/repnz movsw: Invalid instruction prefix mystery

Posted on 2019-08-20, 09:52

by

by llm

in DOSBox General

in DOSBox General

so i think replacing repne/repnz on movs with rep would be the correct asm code for masm resulting in the same behavior but i will stay with db 0f2h, 0a5h for beeing binary equal 😀

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Re: repne/repnz movsw: Invalid instruction prefix mystery

Posted on 2019-08-20, 09:28

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by llm

in DOSBox General

in DOSBox General

MASM got the /Zm option for maximum Masm 5.1 compatiblity (that worked with former MASM version i think) - its shown using /? but it seems not to work - still the error USAM got the -Zm option but also do not seems to supress the error thx for the info: i will use a REPNE_MOVS macro in all places to …

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Re: trouble with a program: cup386

Posted on 2019-08-20, 06:24

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by llm

in DOSBox General

in DOSBox General

for unpacking old dos executables what executables - maybe someone know already how to unpack them no idea (cup386 don't seem to like EMM386) - but have you tried UNP from http://unp.bencastricum.nl/ - well known, works under dosbox and maybe able to unpack you exe

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repne/repnz movsw: Invalid instruction prefix mystery

Posted on 2019-08-20, 06:04

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by llm

in DOSBox General

in DOSBox General

im currently reverse engineering a small DOS 16bit program and stumbled over invalid prefix combinations comming out of IDA/ndisasm when using MASM to assemble it back to code TASM and NASM have no problem to assemble these instructions - but MASM/UASM failing im currious what is the correct code …

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Re: DosBox: Error "not enough memory for internal tables" and how to fight it?   

Posted on 2019-01-23, 06:23

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by llm

in DOSBox Games/Apps

in DOSBox Games/Apps

How much faster is the new exe in you 11k file case, fast enough or still very long to calculate? With some minor tweaks it could be possible to calculate with several running eterna3_32 in parallel or maybe 3.40 or the newest release are better optimized

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Re: DosBox: Error "not enough memory for internal tables" and how to fight it?   

Posted on 2019-01-21, 07:54

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by llm

in DOSBox Games/Apps

in DOSBox Games/Apps

hope the exe is working for you I uploaded another file, it is very "long" -44sec in dosbox/eterna3, 0sec using native eterna3_32 - do you have even larger samples? maybe the timing stuff isn't working properbly -very same result (except the bechmarking) as dos eterna3.exe - use text/binary diff …

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Re: DosBox: Error "not enough memory for internal tables" and how to fight it?   

Posted on 2019-01-18, 15:34

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by llm

in DOSBox Games/Apps

in DOSBox Games/Apps

got your 32bit windows build ready -i configured the source of eterna.for properbly -removed binarydirt from the end of ETERNA.DAT (part of the uploaded files) http://s000.tinyupload.com/?file_id=04179816032306925217 ETCPOT.DAT <- fixed version ETERNA.inp <- sample input from you eterna3_32.exe <- …

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Re: DosBox: Error "not enough memory for internal tables" and how to fight it?   

Posted on 2019-01-18, 06:04

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by llm

in DOSBox Games/Apps

in DOSBox Games/Apps

1. Yes, I can use the latest version of the program. I did not use it earlier because the program had a failure, but I could not understand the reason for this failure. Whether this is an improperly prepared data file, or an incompatibility of software, the absence of certain libraries or …

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Re: DosBox: Error "not enough memory for internal tables" and how to fight it?   

Posted on 2019-01-17, 08:22

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by llm

in DOSBox Games/Apps

in DOSBox Games/Apps

1 and 3: you should use vmware player - its the best and free for personal use, skip virtualbox(oracle) virtualpc, qemu, bochs, ... not worth the try for your case 2. Source is part of the release, can you upload all the files,samples somewhere? Zip file on http://www.tinyupload.com for example 5. …

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Re: DosBox: Error "not enough memory for internal tables" and how to fight it?   

Posted on 2019-01-16, 06:12

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by llm

in DOSBox Games/Apps

in DOSBox Games/Apps

I Use DosBox 0.74 to run the old DOS programm, written in Fortran. Nor any graphics, sound, joysticks, no, only mathematical calculations. I need to take 1500 source files and get 1500 results files. In the first version I called DosBox from the my program each time where the file was ready for …

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Re: DOSBOX Stammering

Posted on 2018-08-07, 14:33

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by llm

in DOSBox General

in DOSBox General

https://www.truebasic.com/bronze says: supported Platforms: Windows XP, Vista (32- and 64-bit), 7, 8, 8.1, 10 - did you try this version?

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Re: Reddit/Reverse engineer dos game supremacy

Posted on 2018-06-12, 19:10

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by llm

in DOSBox Development

in DOSBox Development

i've loaded an exe image in dosbox with the dosbox-debug command and parts of the image data was already changed before executing the first instruction (and the changed offsets are not part of the relocation) does not happen with current svn

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Re: Key/Mouse problems while debugging dosbox-debug is active

Posted on 2018-06-12, 19:06

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by llm

in DOSBox Development

in DOSBox Development

more details, discussion or a bug report available?

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