DEC Purchase Specifications, particularly 23-000A9-01

[Paul Birkel]

-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Mark J.
Blair via cctalk
Sent: Tuesday, July 16, 2019 4:10 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: DEC Purchase Specifications, particularly 23-000A9-01

.....

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!

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>From some notes (origin misplaced!) you'll need a typical access time of
40ns from address, or 20ns from /CS:

    ----
    DEC boot PROMs on Unibus cards are small bipolar fusible-link PROMs

    The A9 types are 82S131 (or MMI6306, 75S171, 27S13, 93448, etc)
    16-pin DIL 512-words by 4-bit wide.
    Pin spacing is 0.1", pin column pitch is 0.3".
    Access times are typically 40ns from address, or 20ns from /CS.
            ____ ____
           |    U    |
        A6 | 1    16 | Vcc
        A5 | 2    15 | A7
        A4 | 3    14 | A8
        A3 | 4    13 | /CS
        A0 | 5    12 | D0
        A1 | 6    11 | D1
        A2 | 7    10 | D2
       Vss | 8     9 | D3
           |_________|

    The F1 types are 82S137 (or TI24S41, MMI6353, 74S573, 27S33, 93453, etc)
    18-pin DIL 1024 words x 4-bit wide.
    Pin spacing is 0.1", pin column pitch is 0.3".
    Access times are typically 40ns from address, or 20ns from /CS.
            ____ ____
           |    U    |
        A6 | 1    18 | Vcc
        A5 | 2    17 | A7
        A4 | 3    16 | A8
        A3 | 4    15 | A9
        A0 | 5    14 | D0
        A1 | 6    13 | D1
        A2 | 7    12 | D2
      /CS1 | 8    11 | D3
       Vss | 9    10 | /CS2
           |_________|

    Note for all types: although the types listed are read-compatible,
    each brand/type may use a very different programming algorithm.

    Also note that these have tri-state outputs; other types (eg 27S13A)
    have open-collector outputs.
    ----

And a potentially useful utility from Eric Smith:
https://www.brouhaha.com/~eric/software/m9312/

I have a vague recollection that someone kludged an 11/84 UBA (M8191) in the
manner that you describe but I can't find the reference at the moment.
Perhaps the memory of someone else will be jogged ...

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