Musings on BabyVAX video

From: Antonio Carlini <>
Date: Sat Jan 18 06:03:00 2003

> I thought so too. But what about SPX? Can it go into a
> pre-M76 VS3100? And what about VS2K SPX? (It would of course
> be very silly in practice, but I'm talking in principle.)

SPX will go into KA42s - although I don't know for sure whether
it was ever sold and supported. It will probably plug into a
VS2K but I have no idea whether it will work (or whether anything
would run on it without more code being written).

> So I thought that KA42 had one big CDAL-to-EDAL bridge
> upfront and the rest of the system except memory was EDAL.
> But I could be wrong, maybe different subsystems have their
> own independent connections to CDAL.

You are probably right - I just threw in "as necessary" because
I don't have a KA42 block diagram handy (in fact, I may not have
one at all - there is not much info floating around on these
and the early UVAX 3100 systems).

> But if KA42 indeed has one big CDAL-to-EDAL bridge upfront,
> the million dollar question becomes: why did the VS4000 M90
> dev team toil to design their own CDAL-to-EDAL bridge (CEAC)
> if there already was one? The only plausible explanation I
> could come up with is that perhaps on KA42 the CDAL-to-EDAL
> bridge was inseparably integrated with the memory controller.

I don't know why they rolled their own. Given that they used
or modified existing designs where possible, I assume that there
were good reasons. Perhaps the existing design was too slow or
took up too much room (this latter consideration was definitely
very important for the -90).

> BTW, I have never found any references to a technical manual
> for VS3100 (any
> model) or for the corresponding early MV3100 models. It looks
> like one never existed. Do you have any more info?

No - and I could never find any even while I was inside
DEC. There must have been *some* such documentation
but it was nowhere I could find.

> Does KA43 have memory on CDAL or on RDAL? I once had one in
> my hands and when I looked on the board to see what chips it

There's not a lot of technical info on the KA43 either!

> Yeah, maybe that was the change. (Was that a typo or was
> EDAQL a chip converting EDAL to SPX's internal bus?)


>But it talks about the X aspects of it and says nothing about VXT2000

Yes, I've read that one and it's not the one. I was sure that there was
an article describing the VXT2000 itself, but I guess since I cannot
find it either on the web or in my docs, I must have
imagined it. Oh well.

Antonio Carlini   
Received on Sat Jan 18 2003 - 06:03:00 GMT

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