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Compressing Win98/DOS7.1 IO.SYS

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#1 roytam1



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Posted 08 May 2011 - 12:06 PM

The Russians have a brief instruction on compressing IO.SYS, as I can't read Cyrillic alphabets, I don't know what is posted.
link: http://groups.google...f7c5dd59abf08f7

#2 0ffer



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Posted 12 May 2011 - 09:26 PM

Packed IO.SYS by Alexander Karmanov
>>Patched to run Win 3.1
>>detailed numbers and offsets to describe certainly won't.
>>the file size of 122896
>>Edit the header of io.sys to pack the code
>>APACK -1 io.exe
>>in out.exe insert the original header of IO.SYS (2048 bytes)
>>Edit the word in the header at offset 8, depends on the size of the packed file.

Packed Size

IO.SYS 75 833

http://rghost.ru/5458107 password RU.DOS


Edited by 0ffer, 12 May 2011 - 09:58 PM.

#3 wendy


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Posted 13 May 2011 - 07:16 AM

From what i read, there is discussion on LZ-DOS (shown to be io.sys + command.com, the latter from PC-DOS 7.1), on the Phelum hack (LBA), steps on how to remove the embedded RLE, and a rather vague set of steps for packing IO.SYS.


AK> If you need technology in brief: 

 AK> cut off at the end as you have written, the title io.sys to be 

 AK> code had to pack, pack APACK -1 io.exe, edit the code in the unpacker 

AK> received out.exe, cut off from him the title, insert 

 AK> The original title of IO.SYS (2048 bytes), edit the word in the title 

 AK> at offset 8 - that's where writing depends on the size of the packed 

 AK> file. I hope the outline is clear ... 

 apack, upx, I wondered when someone will restore komresor used 

in msdos 8, there lzx, with libmspack do not so difficult, 

 would desire.

Unfortunately my wishes do not always coincide with the possibilities ... If 

 existed EXE-packer for this algorithm - is another matter, but there is some C-shnaya 

 Library. Yes, and seems to gain in file size will be very 

 little, if at all. Was thought to do on UPX-LZMA, but LZMA 

so the brake (according to the authors' UPX to ~ 30 times slower than NRV) 

 that the happy owners of some 386 would have to wait a decent 

 while booted DOS:). When winning a 2.5kb compared with apack.

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