mojoehand wrote:
> So far, I have verified that the 16-pin header is indeed for
> connecting to an AppleColor 100 (or similar) TTL RGB monitor. The
> corresponding signals match those on the 10-pin header with the DB9
> connector. This means that the 10-pin header is not for connecting to
> something on the Apple motherboard. That leaves the 2-pin J1 as the
> only connector that might attach to something on the motherboard. I
> still don't know what that might be, however.
> 
> I'm just starting to trace things out, but this is what I have so far.
> Pin 1 of J1 goes to pin 9 of the 74LS175 (quad D flip-flop), which is
> just below J1. Pin 9 on the LS175 is CP (clock). pin 2 of J1 goes to
> pin 3 of the 74LS174 (hex D flip-flop), which is the middle chip
> beneath the 10-pin header. Pin 3 on the LS174 is D0 (data). I know
> this isn't much, and as I said, I'm just starting to trace this out.
> Does this give a clue yet as to what J1 might connect to?

Hmmm--how about a clock (like 14MHz) and video...?  It's strange,
though, that there is no ground on the connector--especially for
high-bandwidth signals.

> A related question -- I know that slot 3 is different than the other
> slots and is tied in with the Aux slot. I thought I read that slot 7
> was also different and had something to do with video. Is this correct
> (on a IIe) or did I misread something? I really need to find a
> readable IIe schematic.

An RGB card for a //e would plug into the AUX slot.  This card sounds
like it's intended for a ][ or ][+.  (And, yes, it does have composite
sync and the color reference on slot 7 only.)

-michael

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