PDP-11/23 Debugging

Noel Chiappa jnc at mercury.lcs.mit.edu
Mon Nov 17 13:55:18 CST 2014

    > From: Ben Sinclair

    > I did not have a jumper on W4, so I added one

Err, adding jumper W4 _disables_ the LTC interrupt; see pg. 324-325 of the
"Microcomputers and Memories Handbook (1982)". (Since you were apparently
seeing LTC interrupts before, it makes sense that the prior state of the
board had them enabled...) If you don't have that book, worth picking one up
on eBay - full of all sorts of useful info.

    > The test I can't run .. is the JKDBDO CPU test. When I try to run this
    > one it doesn't print anything and drops me to ODT at 037526.

Hmm. Probably need listings, or something, to figure out what it's unhappy
about. The only documentation I could find online is the "PDP-11 Diagnostic
Handbook", and various copies of the content there, and it's not very
detailed. (BTW, it's probably 'JKDBD0', not "JKDBDO".)

    > The BDV11 manual says they are controlled through a register via
    > software, so maybe I'm just not running anything that sets them.

That would be my guess too.

    > The only boot rom I have on the BDV11 is a TU58 boot loader, so if it's
    > up to some other boot rom to set that LED register

More likely the system software, not the ROM.


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