Xerox D-series workstations

From: Kevin Schoedel <>
Date: Fri Nov 5 20:28:48 1999

On 1999/11/06 at 12:20am +0000, Tony Duell wrote:
>Well, writing microcode assemblers (and I prefer to work in assembler
>rather than anything higher) is not too hard.

I'll time myself once I find the encodings :-)

>Then of course there's the problem of getting the machine to load the new
>microcode, of getting the OS to correctly use it, etc. It's not a trivial
>job, even when you can write microcode that makes sense.

For the Daybreak, that might be the hardest part. I understand the 80186
loads it on boot, but how or whether one might make things happen in a
running system I don't (yet:-) know.

>It's a pity I can't read .pdf files.... One day I'll figure out how at
>least to handle ones that are scanned images (which shouldn't be too

I think I can find a way to convert them en masse to another format. They
total some 65M, however, so if as I assume you are connecting by phone
(you seem to start posting at 6pm...) you might not want to download the
entire set. If you wish, I'm sure I'd be able to get a copy to you on
CD-ROM or paper at some point in the next few months.

>Knowing the format of the Daybreak microinstruction (and
>whether the sequencer chip is custom as I suspect) would be a great help

That much only requires that I find and read the relevant sections, which
I'll most likely do this weekend.

>Are you _absolutely_ sure about those connections? I assume you've
>checked them visually, and not relied on continuity tests (remember the
>transformer might be shorted).

I was wrong, of course. I had done it visually, but missed a trace under
the body of the transformer, *and* mis-oriented the switch leads when I
checked them. The wiring is actually absolutely straightforward:

   N------------+--1(| t |)5--+----fuse2--A front
   L--fuse1--+--|--2(| r |)6--|--+--------B panel
             | +--3(| n |)7--+ |
             +-----4(| s |)8-----+

(Sigh. I'm still at the point where I can't tell that obviously wrong
things are wrong.) This seems to rule out everything but the transformer
Received on Fri Nov 05 1999 - 20:28:48 GMT

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