DEC Purchase Specifications, particularly 23-000A9-01

Mark J. Blair nf6x at
Tue Jul 16 15:10:29 CDT 2019

I've been studying scanned documents for the M9312 UNIBUS bootstrap/terminator card because of reasons. They refer to Digital Equipment Corporation Purchase Specifications 23-000A9-01 and 23-000F1-01 for the PROMs, and I'm wondering whether those documents have been preserved anywhere? I'd love to see them.

Ok, about the reasons: My PDP-11/34A has an M9301-YF bootstrap/terminator card, which doesn't have bootstrap code for a couple of the newer devices I'd like to use in the system such as RL02 and emulated TU58. The newer M9312 card looks more flexible for changing out bootstraps than the M9301 series.

I'm working on getting my hands on an M9312, but I don't know yet whether I'll be able to get original PROMs for the specific bootstraps that I want. I haven't identified a trustworthy source for blank old-timey bipolar PROMs yet (and I'm not sure if I have a suitable device programmer for them), and I was thinking about making some sort of PROM emulations that I can swap around like they're going out of style. It would probably be helpful (and definitely interesting) if I could learn details about the original part specifications, such as what speed ratings DEC used. I don't have an M9312 in my hands yet, and I'm not yet sure about how rapidly the card performs its little 4-to-16 bit deserialization stunt.

If 70ns access time parts are sufficient for the M9312's PROMs, then I may design an emulation with a 5V compatible 28 series EEPROM. If they need to be faster, then I may need to do something fancier. Or maybe I'll find the original PROMs that I need and then get distracted and wander off. It may well be easier to design a replacement for the entire M9312 card than trying to emulate the individual 512x4 bipolar PROMs, but since when do I do anything the easy way? I sure wouldn't be playing with 40 year old computers if I was concerned with practicality and ease of use!

Mark J. Blair, NF6X <nf6x at>

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