> From: Paul Koning
>> One of the great Dutch achievements in computer science:
> The correct description is "one of the great achievements in
> computer science".
Take that set of things. There's a sub-set which are due to Dutch
people/institutions. That's what/all I meant.
> From: Simon Claessen
> I'm not THAT old... :-)
What, you think I am? :-) It's called 'knowing your field's history', like
knowing what Bohr's atomic model was, if you're a physicist...
Noel
> From: Johnny Billquist
>> http://www.classiccmp.org/pipermail/cctalk/2015-February/003756.html
> Cool.
Sure; glad you liked it.
>> But the QBUS part of _any_ QBUS backplane is not 'directional'
>> ...
>> http://www.classiccmp.org/pipermail/cctalk/2015-February/003757.html
> there is still a question on whether the CPU just pass all signals
> through that you need.
Perhaps I'm confused, but the only QBUS signals which are not 'broadcast'
(i.e. sent down a wired-OR bi-directional bus transmission line to all cards)
are the grant lines. The CPU doesn't pass them through, it originates them -
but memory cards ignore those lines anyway?
> With PMI memory, it obviously works somewhat different, since the CPU
> sources signals in just one direction (hence the reason the PMI memory
> have to be before the CPU)
Actually, the PMI signals are all (I'm pretty sure, but have not checked) just
like most other QBUS signals - 'broadcast' bi-directionally down a
transmission line. The 'PMI memory before the CPU' thing in 11/83's is simply
an artifact of the way 'standard' Q/CD backplanes are wired on the CD side
(used for PMI) - see that second post for details.
In the 11/84 backplane, the PMI memory lines _are_ bussed to all the slots,
just like the QBUS lines, which is why 11/84 PMI memory cards go after the
CPU. (So you could in fact have an empty slot between the CPU and the first
PMI memory card in an 11/84, and it should still work.)
> [the CPU] also interacts/intercepts with all other memory accesses to
> the PMI memory.
My impression is that the CPU does not get involved in DMA access to PMI
memory.
In an 11/83, I gather the DMA devices just do ordinary QBUS memory cycles to
it (see the MSV11-J manual, pg. 1-1, middle). In an 11/84, with UNIBUS
adapter, IIRC the UNIBUS adapter does PMI cycles direct to the memory (but
don't quote me on that, I haven't checked the 11/84 documentation, although
the MSV11-J manual indicates it does - see pg. 1-1, bottom).
> Which is yet another reason why the PMI memory sits before the CPU. If
> you put PMI memory after the CPU, it will instead work as normal Qbus
> memory.
I'm pretty sure that whether PMI memory works as PMI memory or QBUS memory
depends only on what it hears on the busses, and nothing else. If it sees a
PMI cycle for it, it does a PMI cycle; if it sees a QBUS cycle for it, it does
a QBUS cycle.*1 So in an 11/84, where it's on the bus after the CPU, it does
PMI cycles with the CPU because the CPU does a PMI cycle.
(1: Note that the MSV11-JB and -JC variants don't do QBUS properly, and are
PMI only, and so can't be used in an 11/83. I seem to recall hearing it's
just QBUS block mode transfers that they don't do properly?)
Which all does raise an interesting question: if an M8190 is in a system with
a _mix_ of PMI and regular QBUS memory, do accesses to both memories work
fine? (E.g. if it's in a Q/CD backplane with a PMI board before it, and a
regular QBUS memory card after it.)
Something to try, I guess - I have a working Q22/CD box, and plenty of cards
- should just plug them in and try it!
Noel
So I had the Ridge 32 running again (when I went to debug the -12V
supply it had started working again, so I'll take that for now, I
suppose). After running for an hour the SMD drive (a Fujitsu 2312) in
it failed. At power up, the drive spins up and when it attempts to load
the heads, there's a loud *clunk* and the drive then quickly spins
down. (If anyone has any bright ideas, let me know...)
I have a few other SMD drives (just picked 'em up today, in fact) but
they're newer (~825mb) and the Ridge disc utilities only support a small
subset of drives (they do not support providing custom geometries,
because that would be *too easy*.)
Here are the disks it lists as supported; some of these are pretty
insane (CDC 9762? Really? Not sure about the Pertecs either...) but
the Fujitsu's aren't entirely out of the question:
Fujitsu:
2351A (Eagle, don't I wish)
2322
2333
2312
2344
Priam:
806
807
Pertec:
DX 300
DX 332
DX 548
DX 199
DX 265
DX 365
CDC:
9766
9762
Anyone have one of the above they'd be willing to sell/trade/etc?
Thanks as always,
Josh
I managed to get an RD54 going again (a different one to the one I was
having trouble with recently). However, if I try to back it up, the backup
is slow, I get quite a few read errors, and it often makes the beeping sound
that it makes when you first power it on.
Clearly the disk is not that well, but I wonder if anyone knows what exactly
the beep means? Is it a signal that it has reached the correct rotational
speed, or that it has re-calibrated the track position, or something else?
Regards
Rob
I've uploaded some photos from the 2015 DEC Legacy event:
http://wickensonline.co.uk/declegacy/image
Had a great time - already looking forward to the next one. Many thanks to the
presenters (local and remote) and everyone who attended.
Regards, Mark.
p.s. yes, I will try and get a better gallery tool embedded into the DEC
Legacy site. The drupal one I'm currently using sucks.
Hi all, as part of a recent purchase of a group of DEC manuals, I have some
duplicates, which are going free to a good home. (I'd prefer it if they went
to people who didn't have any copies of the manual in question, but I'm not
hard and fast on that.) They are:
EB-26078-41 Microcomputer Products Handbook (1985)
EB-20912-18 Microcomputers and Memories Handbook (1982)
EB-28251-20 Terminals and Communications Handbook (1980)
Email me if you want one. (I will, of course, need your address! :-)
Noel
A few people asking for SMD Drives model specific. What models?
Best regards,
Ed Hogan
Unimetrix Corporation
20371 Lake Forest Drive
Suite A-7
Lake Forest, CA 92630
Phone: 949-215-2475 x101
Toll Free: 800-633-9955 x101
FAX: 949-215-2472
Email: ehogan at unimetrix.com
Web: www.unimetrix.com <http://www.unimetrix.com/>
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