any idea what this schematic is?

Ethan Dicks ethan.dicks at
Sun Dec 21 01:00:47 CST 2008

On Sun, Dec 21, 2008 at 1:00 AM, Gordon JC Pearce MM3YEQ
<gordonjcp at> wrote:
> Ray Arachelian wrote:
> It's a serial port.


>> Would this be the interface between the Lisa and the Mac as related here:
>> <>
> Hmm, the 1981 date suggests that it would a bit early for the Mac...

Not sure about the date, but that's only two-ish years before I seem
to recall seeing an article about the Mac in "Byte" (1983).

> ...and the layout of the PCB suggests an Apple II card...

I  completely disagree.  The location of the power and ground pins on
the schematic are where the Apple II has the address and data buses
(plus +12V, on the wrong pin for the schematic).  Additionally, the
signal names /VMA, /VPA, and E are usual names for MC68000 buses (or
perhaps the 6809), not the 6502.  Plus, suggestively, but not
conclusively, the card form factor doesn't look to me to be something
for the Apple II (the card is too tall compared to the width the
fingers are drawn at).

I'm reasonably certain that A) it's not an Apple II card, and B) it's
a card for some 50-pin-bus 68000 machine.  It might as well be the
Lisa as anything else, but that could be confirmed by cross
referencing the listed bus pins with Lisa documentation.


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