Re: RGB Card Question

["mdj" <mdj.mdj@gmail.com>]

bieling@terra.es wrote:

> > 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 would suspect that the TEXT/GRAPHICS softswitch triggers it.

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

It's possible in this case that the killer doesn't activate until a
video cycle ends or starts. I'd suspect that the colour burst being
absent in the middle of a frame would produce pretty bizzarre results.

Someone would need to hook the machine up to a CRO and examine the
video signal to see what's really happening; looking at a display and
guessing isn't a very good test.

In either case, it matters not - handling colour/mono on an RGB adapter
is done either by a sequence of mode switching or with a physical
switch. Any new design would probably be best to implement both
schemes.

Matt