PDP-11/05 Fault?

Matt Burke matt at 9track.net
Wed Sep 29 19:21:54 CDT 2021

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.



More information about the cctalk mailing list