Re: Second Sight board

[nathan@cco.caltech.edu (Nathan Mates)]

In article <368km0$t2d@paris.ics.uci.edu>, Orion Pax <jlee@ics.uci.edu> wrote:
>Dan Brown (vmbb!pro-newton!pro-dan!danb) wrote this question:
>:        Why the requirement that the SS card be in slot 3 on a ROM 01 GS?  Is
>: there such a requirement in a //e?

>I would expect this has something to do with the way slot 3 has its bus
>addresses or something in the lines that is valid all the time so it can
>monitor motherboard video write activity or something.  About the same
>reason approximately why accelerators and the VOC usually should be put in
>slot 3.

   The impression I got from Baz was that the motherboard just isn't
fully connected up. The video signals are only sent out to slot 3 on
the Rom 01.

   As to accelerators, that was a normally unused slot, so it was
perfectly safe to put a board there without conflicting with any
built-in functions.  (If you've got something plugged into the 65816
space on the motherboard, _all_ of the addresses are perfectly
valid. Think about it :)

   Then, video boards (VOC) came out, and they needed slot 3. So,
my Zip got moved over to slot 01. [Big hint: the connector is very
reversible. If you reverse the connection on the board and reverse
the conection to the 65816 slot, it's exactly the same.]

   Now, when I get a Second Sight, I might have to either upgrade
to a Rom 03, or maybe move the VOC into another slot, provided it
can still overlay a video signal on black. That'd allow me to retire
my GS monitor as a TV, and use a (S)VGA monitor as the main screen.

Nathan Mates




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