Re: IIGS hardware questions

[irsman@iastate.edu (Ian Schmidt)]

In article <CrFDr8.8zz@crash.cts.com> shack@crash.cts.com (Randy Shackelford) writes:
>In article <2tl97u$s22@nyx10.cs.du.edu>,
>Chris Deschu <cdeschu@nyx10.cs.du.edu> wrote:
>
>>	While I was looking over my logic board for the above
>>described problem, I saw something I'd never noticed before.
>>Underneath the power supply, about an inch and a half behind the
>>VGC chip, at coordinates C-4 on the logic board, is a pair of pins
>>sticking out, like for a jumper block. They are labeled "W1".
>>Now, I know there are some on a ROM 3 motherboard in this general
>>location, to disable the control panel CDA. However, I've never
>
>My ROM 01's have those as well. I always wondered what they do but no one in my
>circles knew. Actually the disable the control panel jumper on ROM 3's is 
>labeled S1 and is over in the vicinity of the SCC chip and ADB controller.

According to the schematics in the hardware reference, this jumper when
shorted inverts the phase of the clock to the Ensoniq DOC chip.  There's no
effect either way having it shorted or not on actual performance; who knows
what the apple guys were thinking :)

-- 
Ian Schmidt / irsman@iastate.edu / irsman@cs.iastate.edu
"The look in your eyes as you head for the door is a cold fire" - Neil Peart