Re: magic switch to ARC console?

[der Mouse <mouse%Rodents-Montreal.ORG@localhost>]

Back on May 31 I (quoted and) wrote, of my PWS 600au,

>> You may only power down the machine from ARC (F10), but using the
>> soft reset on the front panel retains the CMOS.
> Then I guess I need to replace the battery.  Needing physical access
> to bring the machine back from a power-cycle is..a problem, in my
> setup.

Okay, today I pulled the machine apart, popped out the CPU/memory/etc
board, and replaced the battery.

Now it won't enter _either_ console.  On power-up, the console gets a
NUL, then, after a pause, a capital A.  Nothing further.

There are eight LEDs on the board, near the accessible edge, next to
the memory sockets.  They are arranged in two rows of four, with the
columns marked 8, 4, 2, and 1; the row nearer the edge of the board
(the top one, with the case in its usual upright orientation) is marked
"MSB".  These go through various codes.  Many of them are displayed too
briefly for me to identify them; the ones that remain long enough for
me to identify are (in hex, based on the MSB and 8/4/2/1 markings) are:

Powerup, dd, flicker, dd, flicker, d0, flicker, cd, flicker, 04.

It stays there as long as I've been willing to wait (certainly well
past the time when ARC or SRM would previously have printed something).
The first and third "flicker"s are accompanied by two ticks from the
machine's built-in speaker.  The NUL is printed very early, roughly at
about the time the first dd is displayed; the A is printed at
approximately the time of the last flicker (changing from cd to 04).

I assume there once existed a document describing these codes.  I even
found a Debian mailing list archive with a message saying that it was
the field service manuals, but, of course, no indication of the meaning
of most codes, nor of where one might find either the manuals or a list
of codes' meanings extracted from said manuals.  Not even a part number
for the manual.  I wandered around bitsavers some but didn't see
anything that looked promising.

I tried reseating the removable board (the one I took out to get to the
battery) in its socket.  I also tried reseating the RAM in its sockets
on that board.  Neither one made any apparent difference.

Anyone got any pointers?

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