Re: Apple][VGA - finally available

[Immortal Nephi <Immortal_Nephi@satx.rr.com>]

> I'll answer both questions in a single message:
> Yes, the a2vga needs an adapter to grab signals from the AUX slot. But there is
> not going to be a clearance problem, because the 80-col card still sits in the
> connector where it used to be. The adapter surrounds the card and sits on the
> other side of the slot's contacts. I can't make you a photo, because I just
> sent the only adapter I have to Henry Courbis, who will present the card on
> KansasFest.

It looks like Apple II VGA card needs to use aux slot because 7 slots
do not have aux information.  I thought that you are supposed to build
80 column card with some connectors.  Both 80 column card in aux slot
and Apple II VGA card in any slot so both cards can be connected
through ribbon cable.  It might helps.  However, you found a way
already to make 80 column work on VGA screen.

> You can't compare the Mega II chip and the Apple][VGA, because the decoding
> done on the Apple][VGA is just a copy of an NTSC TV's color decoder. It is
> analog circuitry! The decoder is somewhat reduced, because, for example, there
> is no need to recover COLOR REFERENCE from the signal because it is already
> present. A similar circuit is used in the PAL color card and the PAL Apple //e
> to partially decode the NTSC signal so that it can be encoded to PAL again.

I know NTSC design and Mega II design are different.  I like both of
them.  I personally myself am disappointed because I can't understand
how NTSC decorder works.  I do understand 100% how video circuit on
both Apple II+ and //e generate video signal to NTSC monitor.

I would appreciate if you have a way to explain how NTSC decorder work
so I can understand in a different way.  Michael J Mahon did his fine
job to provide an explanation.