My AS4100 had free room for CPU; I bought a CPU to someone dismouting an
AS1200. The processor did not work at once; still, AS4100 CPUs (SROM
V2.0) can work in AS1200, so, I was 100% sure the pinout was ok.

After some tries, I understood that the only major difference was the
SROM. The SROM is a small software store in a ROM chip, on the CPU
board. Switching the chips of two CPU inverted also their behaviours.

I send the SROM of a working AS4100 CPU to an electronic guy; it was
originally an XC17128 from xilinx. That chip was no more available in
the required package PLCC20; he bought the XC17256, and put the old
firmware in it.

The CPU now works fine in my AS4100.

***

What I saw just tonight, is that in fact, the cpu #0 of my AS4100 has
SROM V1.1; maybe if I had put in slot #0 a CPU with SROM V2.0 or 3.0, I
could get all of them work without having to write a new chip ... I dont
know.

--
>o_/ DEMAINE Benoit-Pierre (aka DoubleHP) http://benoit.demaine.info/

If computing were an exact science, IT engineers would not have work \_o<

"So all that's left, Is the proof that love's not only blind but deaf."
(FAKE TALES OF SAN FRANCISCO, Arctic Monkeys)