3 Aug
2011
3 Aug
'11
5:13 p.m.
Bitsavers might have a copy of the Unibus troubleshooting guide. It might help.
Paul
On Wed, Aug 3, 2011 at 6:31 PM, Jochen Kunz <jkunz at unixag-kl.fh-kl.de> wrote:
On Wed, 3 Aug 2011 21:14:19 +0100 (BST)
ard at p850ug1.demon.co.uk (Tony Duell) wrote:
This is about
where I am at the moment: I try to figure out how the Run
LED is controled. Unfortunately the scans of the prints are close to
unreadable. The other question is: Does the 8008 microprocessor in the
console interface honor the HLT signal at all? I surely don't want to
go as far as reverse engineer the 8008 firmware.
I am also reading the "pdp11 bus handbook" to educate myself about the
Unibus protocoll. Intention is to hook up a scope or logic analyzer to
the bus and try to capture bus transactions. Unfortunately the book
doesn't talk abut SPC slots and the HALT signals are a SPC only.
--
\end{Jochen}
\ref{http://www.unixag-kl.fh-kl.de/~jkunz/}
The
"Run" LED is always lit. The manual states that examine and deposit
commands are only possible when the processor is in halt state. But
I don't
have the prints in front of me, but is that a possible starting
point? I ssume there's a signal from the CPU to the console controller to
indicate that the CPU is running. With hte CPU removed, does this float
in the 'halted' state? (I assume it does, if the manual suggests resting
the thing without the CPU boards fitted). Maybe you can check this, and
check the input circuitry for this signal on the console controller