These utilities are good for working with game console roms... 

Just put them in your path....

First you should get a copy of the rom into a file..

this can be done with DD... you must put the rom into a socket 
and then use DD to copy from device mem: into a file 

assume you place the ROM in a socket addressible at hex FE000

dd if=mem: bs=16 seek=fe00 count=16 of=file.rom

this will read 256 bytes (16 * 16) (BS * count) starting at FE000 
into a file named file.rom

NOTE.. FE000 is probably where your PCs BIOS rom is, so use this to experiment...

dd if=mem: bs=16 seek=fe00 count=16 | hexdump -C

WARNING... all roms in a PC will be checked for ROM BIOS extensions

if the rom is one of a multi-set of roms, perhaps 16 bits wide,
get both roms into files and then use merge to combine them.

merge even.rom odd.rom of=sixteen.rom

after modifications you can use split to make separate 8 bit roms
with 16 bit data.... 

split if=sixteen.rom even.rom odd.rom

twiddle can be used to manipulation bits... see twiddle.txt

CMOSDUMP is just a program that dumps your PCs CMOSram in a human readable form...

HEXDUMP just displays binary files in a human readable form ....

each program has built in help... type...

HEXDUMP /?  

or

HEXDUMP -h

all these programs are public domain...