PDP-8 diagnostics SR settings?

Johnny Billquist bqt at update.uu.se
Sun Sep 6 07:22:49 CDT 2015

On 2015-09-06 02:39, Charles wrote:
> Looks like I spoke too soon. The dreaded RL8A failure has returned!
> I made a new OS/8 RL02 pack on vtserver (took the expected three hours
> at 9600 baud console speed). Booted up the 8/A, so far so good.
> But then Drive 0 faulted and OS/8 crashed... restarted and it crashed a
> few seconds later again.
> I flexed the middle of the RL8A upwards and the system worked. For a
> while. Then it crashed and wouldn't reboot.
> Back to where I was earlier in the week - won't even allow SerialDisk to
> boot if the RL8A is in the backplane. OS/8 on the SerialDisk virtual
> RK05 works flawlessly if the card is removed.
> Obviously there is still an intermittent which has come back. Maybe
> there's a tiny thread of something conductive stuck under one of the
> IC's and I managed to temporarily clear it as I described.
> Anyhow I am resuming my search for a good RL8A. I have wasted enough
> man-hours on this flaky board.

If it works when you bend the card, I would suspect a bad connection, 
such as a cold solder. Of course, a short is also possible, but I 
wouldn't think that would do it.
While tedious, it might work just to resolder all the components on the 

The other thing to possibly look at is the bus connector. Check that 
there isn't some crap down in the slot. Have you tried the card in some 
other slot?


Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol

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