Re: RGB Card Question

[bieling@terra.es]

Michael J. Mahon wrote:
> bieling@terra.es wrote:
> > mdj wrote:
> >
> >>Jorge ChB wrote:
> >>
> >>
> >>>You can tell if a line has to be interpreted as color/B&W on a line by
> >>>line basis by watching for the presence of the color burst at the
> >>>beginning of *each* line...
> >>
> >>??
> >>
> >>The colour burst is omnipresent in graphics modes. Even mixed mode with
> >>4 lines of text you get the fringy colour bust issues.
> >
> >
> > Yep. You get it, but it does not mean that the color burst is present.
> > In fact, it is not for these 4 lines.
> > What happens is that the color circuitry in the monitor takes a while
> > to shut down.
>
> I just looked at it on a //e, and the burst stays on for all lines
> in mixed mode.

Really ?
The 4 bottom lines are text... Isn't it off while in text mode ?
What is driving the color killer circuit then ?
What is gating the burst in ?

>I suspected that it would, since an intermittent color burst is a
>definite no-no, with potentially unpredictable results for color
>monitors.

It takes a while for the monitor to shutdown the color circuitry.
Try this example in assembly (has to run fast) on a color monitor,
and you'll get a color image all the time (watch the text):

LOOP:
LDA TEXTMODE
WAIT (A FEW TENTHS OF A FRAME)
LDA GRAPHICSMODE
WAIT (A FEW TENTHS OF A FRAME)
JMP LOOP