some one asked if they could write to \device\physmem at the address
c0000
so i got hooked into this
i used physmembrowser (by four-f) to read the entries at that place
Code: Select all
000C0000: 55 AA 40 EB 3D 37 34 30-30 30 30 30 30 30 30 30 Uª@ë=74000000000
000C0010: 30 30 30 30 30 30 30 A2-34 01 9E 2A A2 2A 49 42 0000000¢4.ž*¢*IB
000C0020: 4D 20 56 47 41 20 43 6F-6D 70 61 74 69 62 6C 65 M VGA Compatible
000C0030: 20 42 49 4F 53 2E 20 05-00 00 4E 01 5E 01 6C 01 BIOS. ...N.^.l.
so was playing along
and i happened to open
debug (yeah the old debug.exe in dos box)
i could see the same info that physmembrowser returned being
available in debug too
so i thought i must be able to do an e and change the byte

well before trying i tried to google about disassembling bios
i couldnt find some eyecatching simple explanation
but one of the search queries led me this forum

so was reading through the collected wisdom
and happened to download the VGA SaveBios
by
Code: Select all
..!....Video BIOS Saver ver. 1.0..(C) Copyright
by Garavsky Andrew, 1997...Smell of South Software, Odessa..2:46
and looked through it
i saw it has the same info that the above both showed
at least the first 80 bytes were same ( i did not look further)
so now i was wary of doing
an e address list on debug because i was afraid of thrashing something
with which i have no understanding
but after some flip flops and coin throws i finally did it
and was expecting a bsod or some such awkward happenings

but i see nothing of that sort happened and worst
nothing was written either
and super worst is i get no error or crash of cmd.exe

so i am wondering what actually happened during the
e
i happened to see a lot of flash talks and flashing utilities
and even some hotflash.html
if at all i have to write there should i use one of those utilities
is there some forum where bios tweaking is discussed

btw what can one tweak in these areas
actually i am interested why would the original poster be
interested in writing there
if he wants to write then he should be thinking about
writing some trampoline code that probably runs his code
restores old code and jumps back to do its original business
btw is any papers codes etc are availble on disassembling
the content in these areas

any or every comment posts and flames are welcome
but dont be too hard on flames

btw i am hoping i am posting in the right forum
thanks and regards