29 Sep
2021
29 Sep
'21
5:21 p.m.
On 30/09/2021 01:06, Paul Koning wrote:
Either the diagnostic has a major bug, or you're
running it on a machine it doesn't support, or there is a setup to tell it the
difference which you missed.
What you're seeing is the very first entry in the table "PDP-11 family
differences", appendix B of the PDP-11 architecture handbook. It is the famous
pattern that the assembler rejects with a Z (machine dependency alert) error code.
This particular pattern produces 6342 only on 11/23, 11/20, 11/35, 11/70, J-11, and T-11.
On all others, including the 11/05 and the PDP-11 emulation in the VAX, it produces 6340
as you observed.
paul
Thanks, Paul. The MAINDEC-11-D0NB diagnostic is meant for the PDP-11/20
according to the listing though the same goes for many other diagnostics
which are also applicable to the PDP-11/05. I guess this one is the
exception. There is a newer version MAINDEC-11-D0NC but I can't find a
listing for that one. Perhaps it has a switch register setting to handle
the difference.
I did wonder if this might be a model specific issue and I did various
searches online but didn't find the right info. Thanks for the pointer.
At least I know it's not a fault that needs debugging now.
Regards,
Matt