Re: Apple ][ to VGA monitor adapter board - looking for best color decoding method

[ferdimh@gmx.de]

On 10 Apr., 22:09, "Michael J. Mahon" <mjma...@aol.com> wrote:

> That's why I proposed using a lookup table in SRAM to map the
> Apple video to the display video, but there's no denying the
> additional complexity.  The versatility is *great* though.  ;-)
>

Ouch! I didn't want to sandwich two 7x28cm boards!
And what happens when nothing is loaded into the SRAM?!
But I've thought about doing that in ROM... I'd need a really fast ROM
then (30ns...)
A CYC292 would be right, but I don't know where to get it.
I was thinking about using two "normal" 70ns EPROMs that are accessed
in alternating fashion, but that means: two ROMS, a latching shift
reg, two data latches-> 5 chips. But this would save 2 '74, 1 '157 and
two relays. so I might make it fit. The ROM cold be programmed to do
all modes in one place then.
I still prefer the analog decoding.

Well, I think I said that. This is an expansion card to be plugged
into slot 7 of an Apple ][, ][+, or //e. The //gs is not supported
because of its completely different video subsystem. But if I have
time and a GS, I might consider designing a such a card for the GS. It
would be far more difficult to get a good picture then.

Because of the lack of time, I think I will continue next week...

Ferdinand