Hi -
My first post. I am interested in learning the ropes in regards to modifying a legacy Bios. I’ve tried Google searching a tutorial that will help me understand the basics of bios modding.
In my case, I have Phoenix Bios ver 4.05 built around 1995. This bios supported a custom motherboard from a piece of electronic test equipment. The motherboard supported an Intel 133 MHz Pentium and used a variant of the Intel 430 chip set. As this motherboard was intended to drive a custom, integrated, PCI device, there were no expansion PCI slots available. This motherboard, however, does have an unpopulated spot for installing PCI connector. With this connector installed and few installed jumpers, the bios does recognize a PCI card installed, however, the Bios setup has no way to assign IRQ to the card. My goal is to patch the bios to enable this ability to assign IRQ to PCI devices.
All of the Phoenix mod tools I could find do not support my earlier version (Phoenix 4.05) bios. I am hoping that someone would have some tips as to how best to attack this problem. Are there older Phoenix tools that would support my project? I have some good experience reverse-engineering firmware but I cannot find any tutorial/primer on how these early bioses were built and how they are organized.
I would appreciate any support you have to offer.
Thanks
Jim