Re: Video Coprocessor
On Mon, 10 Nov 1997, KC5TJA wrote:
> > Whenever the MP gets a chance -- at the end of the current memory
> > transaction of the stack processor (SP) -- it fetches the next video word
> > and puts it into PR. In the case it is a jump, MP generates an immediate
> > second memory access go get the video word at the new location. So, the
> > PR is sometimes filled with one memory access, sometimes with two.
>
> Does the video processor have a higher bus priority than the stack
> processor?
Yes. I think I've described how when exactly is the VP request serviced
by the MP.
> If not, then that would explain a large number of video
> effects, like jitter and spurious black lines and stuff
There is one "video jitter" effect explained in my previous posting.
What is a "spurious black line" I have no idea, but I belive that this
might happen.
> (the old TRS-80s
> had this problem).
I'm quite sure the old TSR-80s does not use MuP21 :-)
Cheers,
--
Penio Penev <Penev@pisa.Rockefeller.edu> 1-212-327-7423
