DEC Purchase Specifications, particularly 23-000A9-01

Bill Degnan billdegnan at
Tue Jul 16 15:19:38 CDT 2019

On Tue, Jul 16, 2019 at 4:10 PM Mark J. Blair via cctalk <
cctalk at> wrote:

> 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>

This guy makes them

He may be able to advise answers to your questions if you find the price it
too high.


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