Well, the video is too short. Could it be fake?

interesting, I wonder if this demo will get released

eL_PuSHeR wrote:

Well, the video is too short. Could it be fake?

It could be, but there's no reason to suppose it is - adding colour to a standard MDA card is just a matter of connecting some lines from the attribute latch to the monitor connector, so it's not too surprising that some MDA cards were manufactured with those connections.

There's a lot more information here: http://www.vcfed.org/forum/showthread.php?617 … he-IBM-MDA-card

Interesting! And probably not faked.

MDA and CGA cards use the same CRT controller chip, Moto 6845: http://www.classiccmp.org/dunfield/r/6845.pdf which supports color.

Informative magazine article:
https://books.google.com/books?id=sgKP4GXb1AQ … gisters&f=false

So if you connected two more control lines and modified your bios to reprogram the CRTC registers I guess it'd work with the right software (which they custom crafted for the video).

"According to Programmer's Guide To PC And PS/2 Video Systems (by Richard Wilton, ISBN 1-55615-103-9), some IBM MDA cards included support for colour monitors" https://www.seasip.info/VintagePC/mda.html

Auzner wrote:

MDA and CGA cards use the same CRT controller chip, Moto 6845: http://www.classiccmp.org/dunfield/r/6845.pdf which supports color.

Colour is not within the purview of the 6845 - it just generates addresses and sync pulses. Colour (or lack thereof) is a function of the surrounding circuitry.

Auzner wrote:

So if you connected two more control lines and modified your bios to reprogram the CRTC registers I guess it'd work with the right software (which they custom crafted for the video).

No CRTC register reprogramming was necessary - ejs said the demo was done in QBASIC, and just used the standard "COLOR fg, bg" statement. Reprogramming the CRTC is only necessary if you want to modify the sync frequencies to get an MDA card to drive a CGA monitor (I have done this) but the video used a multisync monitor and the standard MDA frequencies if I understand correctly.

That makes sense. It said "color" in the article and datasheet but I see that's just marketing notes. At a glance I thought it as clocking an NTSC color burst or something.

reenigne wrote:

Auzner wrote:

MDA and CGA cards use the same CRT controller chip, Moto 6845: http://www.classiccmp.org/dunfield/r/6845.pdf which supports color.

Colour is not within the purview of the 6845 - it just generates addresses and sync pulses. Colour (or lack thereof) is a function of the surrounding circuitry.

Correct. Virtually anything that generates a voltage can be used to drive a monitor, sometimes with little or no modification.