Don't forget, there is a jumper on the motherboard that's mono/color if it has one. If you are using MDA or HGC, set jumper to mono. Anything else color is the default.

Cheers,

On my FIC VA-503+ with VIA MVP3 in 90s I had to patch VIA registers to enable access of graphic card registers/memory to ISA. Then I could use softice and swat. Then I switched to 440BX based motherboard with celeron 300 and I couldnt get Hercules to work anymore.
Now I have Shuttle HOT-566 and Hercules I have installed in it doesnt work either, so I suspect I need to find what registers I need to patch in Intel chipset as well.

Pentium 4 (Cedar Mill) with a CGA/Hercules graphics card.

Didn't have a Hercules compatible monitor to test, but CGA does work. Didn't need any BIOS or hardware modifications.

Did the same thing last year, except with a Tualatin since I don't have any industrial ISA boards:

Re: What retro activity did you get up to today?

Would be amusing to see if it's still possible with the LPC->ISA adapter, but I don't have any hardware for that setup.

pentiumspeed wrote on 2023-02-12, 02:01:

Don't forget, there is a jumper on the motherboard that's mono/color if it has one. If you are using MDA or HGC, set jumper to mono. Anything else color is the default.

So this is normal, but I have just come across two 486 boards that are abnormal, different chipsets, but both with a 1.x Version of AMIBIOS for 486. On the FIC 486VC, CGA support has to be enabled by jumper, but it appears the jumper is only for CGA, not EGA/VGA also... but I have not tested that, board was otherwise flaky. Then the other board, ISA486GXI, no jumper can I find, but when booting with CGA it says the jumper is set wrong. It sorta works but you gotta press F1 to continue and it has some peculiarities, blanking the screen doing directory listings was one. Anyway, putting an EGA/VGA card in with no jumper changes had it working fine in EGA. So this one too expected a "CGA only" jumper. Somewhere in the docs I was reading with reference to these two, it said MDA/EGA/VGA were supported in one config, but CGA needed jumper set. Which is weird, because as stated, mono/color was the normal jumper option. There is a BIOS configuration thing on first setup page too, it autofills that normally, but you might need to set it on other BIOS, whereas on XT there may be more than one jumper to fully set CGA or Mono, because it doesn't got a CMOS RAM to setup those other parameters in.

Therefore, if you want to run CGA in 486 era, and these also were late 386 chipsets, then maybe you either want to avoid AMIBIOS boards or double check that they have full jumper support. However good news is, that maybe going forward from there, AMIBIOS might not need jumpers changed to run MDA/Herc, but autodetect and run same a EGA/VGA... but you might be SOL for CGA on later AMIBIOS ... further data required.