BIOS – Initial Look

To make the TFT conversion complete, we need to modify the ROM bios to have the correct configuration values for the new display.

After some research I learned of the BMP (Bios Modification Program) provided to OEM’s by Chips&Technology for customizing the CT65535 video bios. It is simply a program that allows you to customize the bios binary. I was not able to find the BMP file for a CT65535 only a CT65545, however it was easy to see what it was doing and confirm that I had located the correct bytes within the video bios I had dumped from C000h.

I am expecting to find a copy of this video rom on the intel flash chip. I do not have the correct TSOP-40 for my ChipProg-40, however I will receive it next week and will dump the contents of the flash to confirm its contents and locations.

For my purposes I am fairly confident I will be able to edit the values, reprogram and put the chip back on. This is not ideal though so the goal is to flash/patch it with a program. I have been reviewing the xpatch.exe to understand how this is possible. I will not attempt anything until I have verified I can backup and program the chips off the board.

This is a disassembled version generated by Sourcer. This is VERY preliminary. I am also investigating with IDAPro 5.0 Free, which properly opens a MZ executable.

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