[Patch] Sigma Designs Color 400 video card

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JohnElliott
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[Patch] Sigma Designs Color 400 video card

Post by JohnElliott » Sat 13 Oct, 2018 1:00 am

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:
Image

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.
Attachments
sigma400.patch
(35.35 KiB) Downloaded 26 times

SA1988
Posts: 227
Joined: Wed 30 Apr, 2014 9:38 am

Re: [Patch] Sigma Designs Color 400 video card

Post by SA1988 » Sat 13 Oct, 2018 11:13 am

Quick question, does this have a bios?

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JohnElliott
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Re: [Patch] Sigma Designs Color 400 video card

Post by JohnElliott » Sat 13 Oct, 2018 11:39 am

Quick answer: Yes, it does.

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JohnElliott
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Re: [Patch] Sigma Designs Color 400 video card

Post by JohnElliott » Sat 03 Nov, 2018 12:10 am

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++) 
                        {

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SarahWalker
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Re: [Patch] Sigma Designs Color 400 video card

Post by SarahWalker » Tue 13 Nov, 2018 6:54 pm

Merged at rev 1197.

shermanp
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Re: [Patch] Sigma Designs Color 400 video card

Post by shermanp » Thu 15 Nov, 2018 11:35 am

SarahWalker wrote:
Tue 13 Nov, 2018 6:54 pm
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!

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