MSDOS Source code leaked

[Bob]

Control Systems made an Artist 2 card which was ega like and supported genlock in both NTSC or PAL
but not both there was a coil and a cap that had to be changed.
It was sold/used for the video overlay of title info on live video. 
There was a video titleing system that used it, I forget its name.
I did an Autocad driver for it in about 1985 or 86ish to do video traceing.  
Still have a few somewhere in the basement.

The other Bob


On Fri, 13 Oct 2006 22:45:09 +0100 (BST), Tony Duell wrote:

>> 
>> On Fri, 13 Oct 2006 13:43:42 +0000, Jules Richardson wrote:
>> 
>> >That's interesting, though. IBM must have believed that the 5150 would be a 
>> >global product and I'd expect that was the plan all along - so why put 
>> >circuitry on there for one market only?
>> 
>> 
>> I do not think there was ever was a PAL version of the CGA card.

>There wasn't. In fact I've never seen a PAL version of any classic 
>IBM-compatible video card.

>It was possible to reprogram the 6845 registers on a CGA card to give 
>European TV timing, albeit still with NTSC-like colour output on the 
>composite connector. I have -- somewhere -- a box that plugs into the DE9 
>(TTL RGV output) connector on a CGA card and which encodes said signals 
>to PAL. The result (after repogramming the 6845) is a PC that can display 
>on a European TV set.

>> As far as I know the CGA card was the only one dependant on the base clock freq being right on.

>A few other cards use the OSC signal from the ISA connector, but AFAIK 
>none of them depend on the exact frequency like the CGA card does.

>> or It would loose color burst. I always thought the 4.77mhz was chosen because it could also be used as the
>> clock ref for the video.

>Absolutely. The mater clock is 14,xx MHz. That was chosen becasue it's 4 
>tiomes the NTSC subcarrier and the division by 4 gives the quadrature 
>signals needed to make a simple NTSC encoder. The CPU clock is the same 
>master clock divided by 3 (I have no idea why the Intel clock generator 
>has a /3 stage in it...)

>-tony