At 09:55 AM 8/7/97 -0700, you wrote:
>
>>So how does the Color Card interpret the 12-bit color data it get from the
>>CPU ??? This has been bugging me (no pun intended) for some time.
>
>Zonn's latest hardware description talks a bit about the color conversion.
>Since I have to do clipping now, looks like i'm just going to implement
>the whole thing now with a uP and two DACs, and do the whole thing in
>software. It does have the advantage that you can use it as a test pattern
>generator, too :-)
>
>My current thought is to have two 12 bit input ports, and have the uP
>watch the state of the start, end signals and an intensity port.
>
>One thing I was wondering, Zonn, is if the 12 bit start/end values are
>ever not at the endpoints of the vector being drawn. Do they ever
>send endpoint data farther out than the actual line end, and use the
>line timer to clip to the visible endpoint.
They *always* set end points way beyond that of the vector being drawn, and
then clip the lines using the timer. That way they display only the linear
part of the R/C charge slope.
Without having access to the internal timer calculating the length of the
vectors is going to be a little envolved, you'll have to do a realtime plot
of a charging capacitor to keep up with the C-CPU.
-Zonn
