Many thanks for the reference PDF, mine is one of the first ones from '92, a 6384-Mxxx, with a integrated ISA Tseng ET4000AX.
I had already found the greyhost mirror for the valuepoint BIOS update floppies, if you write a floppy with these executables and open the image file you can see that it begins with the video bios, the problem is that I couldn't found one that begun with the ET4000AX.
In the URL https://www.wimsbios.com/forum/other-bios-upd … date-t2562.html someone says that according to some document in a broken link the BIOS is not flashable, indeed, in the attached photo you can see that the official BIOS is burned on two 27c512 EPROMs, so that explains there is no image on the BIOS update floppies from IBM. There are also BIOS collector pages that list 6384-Mxx as "wanted BIOSes"
I think I have two ways of solving this:
- Finding someone with a 6384-Mxx model with a Tseng ET4000AX that graciously dumps the bios. This would be beneficial too for people with this PCB since a failure in the EPROMS would leave them with the same problem.
- Getting a BIOS that is very close (I don't think a VESA bios would be a good idea) and change the video BIOS with one from a Tseng ET4000 that has the same size. I have to hex edit and check some BIOSes first to see if this is feasible.