[Patch] Sigma Designs Color 400 video card

[JohnElliott]

The Sigma Designs Color 400 has only one claim to fame that I'm aware of - the only 4-colour driver for Windows 1.0 that I know of was written for it (SIGMA4.DRV).

I implemented it to see what Windows 1.0 looked like in 4 colours:


But I thought I might as well make it up into a proper and reasonably complete patch.

Notes:

• If your system's BIOS supports video ROM shadowing, disable it before switching to the Sigma card - the card does not work with its ROM shadowed.
• The card uses non-maskable interrupts to implement hardware-level compatibility with CGA. If you find this leads to instability (for example, the PC hangs when trying to scroll the screen) this can be disabled in the card configuration - this will leave it compatible at the BIOS level only.

[SA1988]

Quick question, does this have a bios?

[JohnElliott]

Quick answer: Yes, it does.