Acer Laptop BIOS - LZMA Compression derivative ? (2005)

Hi there !

1st of all, I know there are other forums, like MDL or biosmods, that are exactly for this kind of questions, but the problem is, Im all alone on those forums with experimenting with this bios.

I really want to change the Splashscreen / Boot Logo of this bios, as its built into my MAME Arcade machine.

Hence I now dare to try to ask on assembler, if maybe someone might be able to determine the compression algorythm of this file, by maybe comparing it to the nearly identical other bios files or even dissassemble the small flasher exe files that I found "compression" infos in...but enough for now.

In short :

I have a Acer Aspire 9500 Laptop from 2005 which has a "Insyde MobilePRO Bios 4.20.10."

A "not so well" documented BIOS, probably some derivative of LZMA LZHA LZSS LZ77 compression used,
but Im not 100% sure and I reached the end of my "experimenting".

I cant find a fitting fileheader, but I found similar/identical BIOS files, one even without compression, that can be viewed and editet with the desired tools. Also the splashscreen / bootlogo.

The original thread can be found here :

https://forums.mydigitallife.info/t...files-(2003-2006)-MobilePRO-4-20-10-(No-H2o!)

I reached my limits of hexediting and testing all kind of tools.

Any help/info is appreciated. I dont ask you to "do all the work", I just hope for any kind of additonal info or a holy samaritian that has some iDA experience maybe...or...anything

 

LZMA decoder is simple. But PPMd decoder is complex. LZMA2 is better than LZMA. LZMA2 compression does not replace (supersede) LZMA compression, but LZMA2 is merely an additional "wrapper" around LZMA. With LZMA2, data is split into blocks, but each block is still compressed by "normal" LZMA. Because individula blocks are compressed separately, processing the blocks can be parallelized, which allows for multi-threading. LZMA2 also allows "uncompressed" blocks, to better deal with "already compressed" inputs.