Good haul of old pc stuph

[Chuck Guzis]

On 12/20/2005 at 9:07 PM Jim Leonard wrote:

>(I say that and, looking at my CGA card in graphics mode, there are
>single-bit errors twitching on and off -- RAM tests okay so I guess the
ramdac has
>blown a gasket somewhere)

Ramdac? I The output of the CGA was plain RGBI digital, buffered through an
LS244.  There is a composite output, but it's sort of a simple-minded
resistor adder network fet to the base of a 2n3904 to so some level
shifting.  Best recheck your RAM--and remember that writes to display
memory on a CGA can occur only during the retrace interval or they produce
"snow".

Cheers,
Chuck