That module was specifically called for in the RH11-AB dual-port Unibus-to-MASSBUS
interface as the Unibus B terminator. See RH11-AB_OptionDescr.pdf, Section 4.24 (page
4-32/33), which has a fairly lengthy write-up.
From: cctalk <cctalk-bounces at classiccmp.org> On Behalf Of Mattis Lind via cctalk
Sent: Friday, February 25, 2022 2:29 AM
To: Noel Chiappa <jnc at mercury.lcs.mit.edu>; General Discussion: On-Topic and
Off-Topic Posts <cctalk at classiccmp.org>
Subject: Re: Is The M9312 Boot Module Essential?
What about the M9300 board? Do you have an idea what the purpose is of that card? It look
a bit like a M9302 but with more logic on it and a few jumpers and a LED. It also have a
delay line and a monostable flip-flop.
Here is a photo of a (dusty) M9300: