Is The M9312 Boot Module Essential?

[Ethan Dicks]

On Sat, Feb 19, 2022 at 4:40 PM Fritz Mueller via cctalk
<cctalk at classiccmp.org> wrote:
> > On Feb 19, 2022, at 12:11 PM, Fritz Mueller <fritzm at fritzm.org> wrote:
> A few additional details, in case it is helpful:
>
> IIRC, the 11/34 doesn’t have SACK timeout implemented in the CPU cards (the /34A did add this, however.)  So without an M9302 on the far end of the bus, the CPU could hang in a situation with an unacknowledged grant (which I think would be somewhat rare, but possible).  I believe it is possible to boot an 11/34 at least as far as a ROM boot monitor with a non-SACK (M930 or such) terminator on the far side.

Thank you for bringing this up - I have a stack of KD11-E and KD11-EA
board sets (and MOS memory and all the other things).  I've been
trying to get them to work in a BA11-L that started off life as a
PDP-11/04 and I've swapped the DD11-DK for a DD11-P backplane but I
wasn't having any luck getting things to run.  I did find a bad 7402
in the limited function front panel but that was the only fault I
found (so far).  I've checked the grant chain but what I haven't done
is ensure I have the right combo of terminators and CPU cards.  I'm
used to configuring machines, but I honestly forget if the experiences
I had in the 80s were 11/34 or 11/34A.  This gives me something to go
back and check.

I was about ready to start hacking on an M9302 to sniff out the SACK
logic.  Now I'll go back and check the docs and make sure I'm putting
together a set of cards that's going to want to play nice with each
other.

I have plenty of dual-height grant cards.  I'm definitely _not_ having
issues with NPR.

Thanks!

-ethan