11/34 troubles

From: Chuck McManis <cmcmanis_at_mcmanis.com>
Date: Mon Dec 18 20:19:00 2000

I hate it when I do this.

So I started playing around with the 11/34 and discover that 2 bits aren't
being set on the words I try to load into memory.

I guess it is perhaps bad memory, I don't have a way to test it other than
to load in a program from the front panel, so I pull the memory and replace
it with 64KW that are known to be good. Now it shows the top 4 bits as
being stuck on. I pull the memory, blow out the connectors, look for loose
dirt etc that I've missed, reseat the memory but no joy. Everything else
seems to be working so the next suspect is the KY-11B, if it had lost a
buffer it could exhibit this behaviour. I pull the KY-11B and check it out,
it looks ok so I clean out the connectors where it is seated and
re-install. No joy, 4 bits stuck.

Now I'm really irritated, so I take the KY11B from my working 11/34 and
replace it, great all the bits work. Ok so I've got a KY11B to fix. Not too
much of a problem since it is pretty simple. I put back the original memory
and now I get BUS ERR whenever I try to touch memory. Ok, figure the memory
board was bad and put the good board back in so that I can work on the RL11
but wait, now it also gives me a BUS ERR indication. I check to make sure I
haven't dislodged any of the stubby grant cards, they are fine, pull the
terminator and move it up to the end of the first back plane. Still I get
the BUS ERR indication. ARGH!

--Chuck
Received on Mon Dec 18 2000 - 20:19:00 GMT