Date : Mon, 06 Mar 2006 00:25:47 +0000
From : Fragula <fragula@...>
Subject: 64 bit vector second processor.
Hi Mike!
> < AAmeeting mode >
>> "I am a BBC sad case and my name is Mike"
>> </ AAmeeting mode >
<grin> Almost did that yesterday, but thought it was a bit ott, me being
the moderate and restrained chap wot I am. ;->
>>> > American friend reckons he can get a formal logic spec for a Cray1/1A.
Sounds handy! I have a block diagram of the processor itself someplace..
Probably a large swathe of the tech manual if the truth were to be known.
>> 12.5nS clock cycle, 64 Bit word, 1Meg + WORDS of RAM.
Expandable to 4!
>> 200,000 gates (all
>> ECL).
Hmm. Didn't think it was quite that many.. 134,000 springs to mind, more
in the production version though.
>> Wire quantised in lengths of 1, 2, 3 or 4 feet. Original drew 115KW
>> from a 230V 3 phase primary, 12 phase polyphase secondary, motor
generator
Yup. 400Hz "Mains", feeding smaller supplies housed in alternate
"seats". 400Hz meant the local supply transformers could be much smaller
and more efficient. I also vaguely recally that the voltage between the
gensets and the transformers was fairly high, to keep the cable diameter
managable.
>> Took 39 square feet of floor space
A 32 sided polygon, but roughly circular, 103.5" in diameter to the
outside of the "most expensive seats in the world". Well actually its a
horseshoe shape that you can walk inside too. But that's the footprint.
>> - quite small.
Compared with the CDC 7x00 that it was taking on, miniscule!
>> Uses boundary scan test system.
.. which kinda evolved into what we now call JTAG.
>> Has own minicomputer for IO.
Yep. All the big Crays do.. I don't know about the 1 or the XMP, but the
YMP and ELs was a VMEbus 8MHz 68000 thing, that literally clocks the
kernel into memory on the "second processor" (oohh.. am i bitching?)
Later Crays, though I don't know the changeover points (i.e. J-1 through
SV-1ex at least) bootp/tftp via a dedicated ethernet port, and get
their kernel down, from a little SPARC workstation, though they do have
local disks at runtime, Later still they boot from an SGI box, which I
hope for the sake of global security isn't ever connected to the LAN,
never mind the internet! Hmm. its quite possible that the production
Cray-1 used a 6502, or a PDP-summit.
>> His Kink? He wants a scale model of a Cray 1.
Sounds remarkably sensible to me!
>> A scale model that actually works
Of course.. otherways its just an ornament.
>> A talk with engineering reps from some of the FPGA stars got them all
>> thinking.
Ahh.. Small world.
>> Major problem, as always with 64 bit, is lack of IO pins. Still,
>> we can get 6nS Static RAM, (running Motorola DSP at 80MHz, needed 7nS
to get
>> 0 ws), and probably enough FPGA content to implement the thing. It is
a form
>> of RISC after all.
Ahh.. well the Cray 1 "round robins" its (4 banks IIRC) of RAM, has lots
of prefetch buffers and stuff. Seymour C was a /big/ fan of low memory
latency, in fact, that was one of the biggest advances at that time, and
something Cray Research stayed ahead with until they got distracted with
the T3D/T3E (Alpha based NUMAish boxes)
I reckon we could even use the original Cray layout at
>> 1/8 or 1/10 scale. Present thoughts revolve around what to do for
host IO?
What has a TUBE ULA! Duh!
>> It would be expensive.
But fun.
>> But it would be a very cool toy.
But not that fast.
Unless it went in one of the high-end vertexes, and had a bunch of
really cool memory stuff in front caching some commodity DDR-3 or
summit. Ok.. i know that shoots the latency but fast SRAM is SO
expensive and SO unavailable to mere mortals.
>> (But for now my personal ambitions lie with one of Sprows ARM Co-Pro's)
>> By the way if you think we're obsessives, take a look at what the
owner of
>> Armari collects:
>> http://www.hexus.net/content/item.php?item=903&page=2
Hmmph.. I /really/ tried to buy a two year old 12 processor/3 rack SV-1
on Ebay (it was in Reading) back in Jan 2004, the 9th IIRC. Took the day
off, got up real early, started costing up the transport (van, fork
lift, hard pallets, couple of experienced humpers, came to about 500 sobs.)
It was about 11am.. Some idiot knocked my door and wanted to talk about
my complete disregard for planning permission or somesuch, I got back 5
seconds before it went under the hammer. £3900. Might have had a fight
on my hands though. Buyer was from Maryland U.S.A., not that far from
Fort Meade <nudge nudge>, as I found out when I mailed him to see if he
had cold feet about the deal (and to try to give him some, trolling out
240V, 50Hz, Transport costs and risks, etc. to no avail.)
Ahh.. it was the fifteenth.. I was so gutted, I took a screen cap.
Would have made a great 2nd processor for the beeb.
--
(Sorry if I top-quote occasionally, the b@...*rds make me use LookOut in
work.)