[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.

[JohnElliott]

A bugfix: In the 80-column mode, the cursor was only being displayed on even-numbered columns.

Code: Select all

--- vid_sigma.c.orig    2018-11-03 00:03:21.290695326 +0000
+++ vid_sigma.c 2018-11-03 00:07:38.479033716 +0000
@@ -441,7 +441,7 @@
 //             {
 //                     pclog("[%x:%x]%c", cols[1], cols[0], chr);
 //             }
-               if (drawcursor && !(x & 1))
+               if (drawcursor)
                {
                        for (c = 0; c < 8; c++) 
                        {

[SarahWalker]

Merged at rev 1197.

[shermanp]

Merged at rev 1197.

Just a heads up, I noticed when preparing my VHD work against the latest revision that the platform specific Makefiles haven't been updated with the changes made in this revision. Might cause some grief for those attempting to compile!