Deciphering PDP-11/05 ZQKC (Instruction Exerciser) MAINDEC failures...

Pete Turnbull pete at
Mon Nov 9 16:44:02 CST 2015

On 09/11/2015 21:42, Josh Dersch wrote:

> Thanks, I should have thought to check the revision codes in the first
> place.  Looks like the Bitsavers docs are from revision C; I've been
> running the paper-tape version that's on Bitsavers (
> which is labeled as "maindec-11-dzqkc-e-pb" which looks like it should be
> Revision E (which is fortunate!).

Yes, Revision E.  XXDP diagnostic files are labelled with the first 
character denoting the type of system/processor they're supposed to run 
on, the next pair denotes the device they're to test, the fourth denotes 
which test it is within a set, and the last two are the version number 
and patch level.  The leading D in the title stands for "document" or 
"documentation" IIRC and isn't part of the diagnostic name.

The specific diagnostic is usually something like (in this case) 
ZQKCE0.BIN if it's on a disk, but old paper tape titles often don't note 
a patch level.

Z means it should run on any processor
QK denotes a CPU diagnostic
C means it's the third of a set intended to be run in sequence
E is the version "number" (5th version, or 4th revision if you like)

Usually DEC changed the version character (always a letter) if things 
like entry points or error halts or routines moved or changed, and just 
changed the patch level (always a numeric digit) if things like 
locations of error halts remained the same.  So ZQKCEn will have 
significantly different code and error halts than ZQKCCn.

Interesting that ZQKB is in that tar file along with ZQKC, but ZQKA isn't.


Pete Turnbull

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