rasteri wrote on 2023-09-29, 22:46:Also it seems the GBS-8200 upscaler with gbs-control firmware is happy to sync to these extended modes if you need a cheap solut […]
Show full quote
- 640x480 and 752x410 graphics modes (on multisync monitors that can do 25/29KHz)
- 60 row text modes (on multisync monitors)
- 120 and 132 column text modes (1080/ 1056 pixels wide), some of which work on regular CGA/MDA/EGA monitors! (15/18/21KHz)
- 640x480 Drivers for Autocad, Windows 2.0, Lotus 1-2-3 and more
- PC Paintbrush IV supports it (because of course it does)
- Can even kinda emulate some VGA modes (11/12)
- Based on the same CS8240 chipset as a bunch of other cards but it has some trickery in its BIOS/drivers for the high resolution modes
Also it seems the GBS-8200 upscaler with gbs-control firmware is happy to sync to these extended modes if you need a cheap solution for superEGA. (Actually I dunno if this qualifies as a superEGA card like the Genoa chipset)
Why wouldn't it qualify as SuperEGA? The point of SuperEGA is that it is an EGA card that has higher dot clock frequencies available, which enables higher resolutions, in both text and graphics modes - and this is exactly what your card does!
In your case, the extra clock generator is the 24MHz crystal oscillator. A standard EGA card only has the 16.257MHz oscillator on board. Both your card and the standard EGA card are also able to pick the 14.318MHz clock signal from the ISA bus OSC pin. As another standard feature of the EGA architecture is being able to use a clock injected at the "feature connector" (the 32-pin socket at the top of your card), there also exist "132-character upgrade modules" that work on most EGA cards by injecting a 24MHz-ish clock into the feature connector and then using a BIOS extension loaded into RAM to enable the 132 character modes. With your card, support for 24MHz clock is obviously designed. The 132-character upgrade module might exceed the design clock of standard EGA cards (basically overclocking them) and could cause random issues.
rasteri wrote on 2023-09-29, 22:46:
Anyone know if there are other CS8240 cards that do these extended modes? And if not, perhaps we could force them to by using the Vega Deluxe BIOS and/or drivers?
Any CS8240 card with sufficiently fast RAM, and a 24MHz oscillator added to it, could run these modes. The BIOS likely requires the extension to 6 DIP switches (a standard card only has 4 DIP switches) and the extra switch, which would need to be bodged on a standard CS8240 card to enable full configurability. With slight changes to the BIOS, you can likely hardcode the extra switch settings, and change from "on-board 3rd oscillator" to "feature-connector clock", so that any CS8240 card with a 24MHz clock plugged into the feature connector will support these modes.
