MicroVAX 2000 ROM placement question

David J. Cooper trs80 at marmotking.com
Wed Sep 15 21:10:27 CDT 2010

Why, yes, I do have many Microvax 2000 motherboards.

What numbers do you have on your ROMs?  I seem to have a variety of numbers 
on various boards.  Maybe I can find a match.

----- Original Message ----- 
From: "Ethan Dicks" <ethan.dicks at gmail.com>
To: <classiccmp at classiccmp.org>
Sent: Tuesday, September 14, 2010 11:05 PM
Subject: MicroVAX 2000 ROM placement question

> Hi, All,
> I've been trying to dust off a MicroVAX 2000 for VCFmw, and so far,
> all I've accomplished is literally getting the dust off.
> This unit was one I tried to install the SCSI-enabled patched boot
> ROMs in some time back.  I _thought_ I had arranged the original ROMs
> in the same pattern, but it's possible with all the swapping, I got
> some mixed up.  I have checked (and re-downloaded) all the ROMs I have
> - one factory set (23-092E7-00 through 23-095E7-00) and one patched
> set.  Cross-checking with the Technical Reference manual
> (EK-VTTAA-TM-001) from Bitsavers, I have verified that all ROMs have
> reasonable contents in the first few bytes (there are three signature
> bytes, among other things).  No matter which set I have installed, I
> cannot get the console to respond with the self-test info.
> Does anyone have a photograph of a KA410 board where the labels on the
> ROMs can be read?  Alternately, does anyone have any docs with part
> numbers?  I'm reasonably certain that the underlying hardware is
> functional and that I just need to re-install the ROMs correctly.
> Yes, I could try the lucky-dip method, but one of the ROMs is rather
> difficult to pull (owing to the memory interface connectors), and I'd
> rather not break a pin off while sequencing through a dozen chip
> swaps.  I'd like to _know_ what goes where before I proceed
> (especially if I am wrong and I _do_ have a hardware fault).
> I don't have any video cables handy, but in case it does come down to
> testing with a tube vs a console terminal, I have a four-plane video
> interface in addition to the mono frame buffer all KA410s come with.
> I had just thought that it would be easy enough to use a BCC08 console
> cable and go from there (it's worked before).
> Thanks for any tips or pointers,
> -ethan
> P.S. - I've been delving into the guts of the machine deeply enough
> that I'm musing about what it would take to make a 16MB memory board
> that didn't respond in the lower 2MB (to work with the on-board
> memory).   Static would be easy to interface, but the KA410 _does_
> generate and pass along refresh signals, so something with 30-pin or
> 72-pin SIMMs shouldn't be that hard to whip up.  I'm only considering
> it because my largest memory board is 4MB, and the current prices for
> an MS400-CA (12MB DEC board) are more than I'm personally willing to
> pay - I'll do without first (which is what I'm already doing ;-)
> P.P.S - this would probably all be moot if I had a SCSI-based MicroVAX
> slab of some sort, but I just haven't been in the right place at the
> right time.  Perhaps some DEC gear will make an appearance at the
> VCF...

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