Boot Rom for KDF11-BA

From: Douglas Taylor <>
Date: Sat Oct 23 11:22:43 2004

At 03:10 PM 10/16/2004, you wrote:
>On Oct 11 2004, 3:51, wrote:
> >
> > Hi,
> >
> > Does anyone have a KDF11-B3 boot rom or any other version which
> > can boot RX33 or an MSCP device on my KDF11-BA. I will pay for
> > that and I will be very thankful since I have not to buy a Eprom
> > programmer to burn the immages.
>KDF11-B3 isn't one ROM, it's an upgrade kit consisting of two EPROMs
>plus instructions. It's more usual to refer to the ROMs themselves by
>the actual numbers or the processor suffix. The ROMs in the -B3 kit
>are 23-183E4 and 23-184E4, as far as I remember; that's the -BF
>version, but most versions of the KDF11 ROMs work with MSCP devices.
> For example, people have used RD31 drives on an RQDX3 with -BE ROMs,
>although it wasn't officially supported until -BG. The next version
>was 23-380E4 and 23-381E4, which would make the processor a KDF11-BG.
>There's a list of ROMs at
> (see the file called
>You can see which revisions officially support various MSCP devices in
>Micronote 43, which you can find in various places including
>BTW, the EPROMs for a KDF11-B are unusual 24-pin 8Kx8 devices; normal
>2764-style 8Kx8 devices will not do because they're 28-pin.
>Pete Peter Turnbull
> Network Manager
> University of York

I looked into this and found that the people who fool around with old
arcade video games have the same problem with EPROMs, here is one fellows'
solution to using a standard 2764 PROM in place of the rare Motorola 68764
(which I think is the one on the KDF11-B quad CPU board). Haven't tried it
though. I could never find the pin out of the Motorola part.... BTW, my
PROM programmer had no problem identifying and reading the 24 pin DEC Prom,
I guess if I could find a blank one I could burn it.

Doug Taylor

You Build It: Hero Rom UpgradeYou build it: Hero Rom Upgrade
OK so you downloaded the new ROM version, but you cant find a 68764 (8K
Eprom in
24 pin package). Well here is a little conversion you can do to allow you
to use
a 2764 (8K Eprom in 28 pin package).

  1 tie high (+5)
  2 tie to socket #21
  28 tie to socket #24
  27 tie high (+5)

   24 Pin 28 Pin Notes
    Vcc 24 26 N/C OK to pass through
    A8 23 25 A8 OK to pass through
    A9 22 24 A9 OK to pass through
    A12 21 23 A11 Socket to prom#2, pin to socket #18
    E 20 22 OE OK to pass through
    A10 19 21 A10 OK to pass through
    A11 18 20 CE Socket to prom#23, pin to ground
Received on Sat Oct 23 2004 - 11:22:43 BST

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