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How fast was the Cray?
Posted: Fri Sep 23, 2016 12:57 pm
by Sean Evans
Re: How fast was the Cray?
Posted: Fri Sep 23, 2016 1:12 pm
by hgm
About as fast as my phone.
That doesn't say it all, though. The Cray had wonderful memory bandwidth, and could stream 64-bit data from and to memory at the clock speed of the CPU. Modern CPUs can only do that from their (tiny) level 1 cache.
Re: How fast was the Cray?
Posted: Fri Sep 23, 2016 2:34 pm
by Vinvin
hgm wrote:...
The Cray had wonderful memory bandwidth, and could stream 64-bit data from and to memory at the clock speed of the CPU. Modern CPUs can only do that from their (tiny) level 1 cache.
That was a reason for the high price of this machines : memory !
Waiting for MRAM (
https://en.wikipedia.org/wiki/Magnetore ... ess_memory ) on PCs : 2 ns access time !
Re: How fast was the Cray?
Posted: Fri Sep 23, 2016 3:02 pm
by Laskos
hgm wrote:The Cray had wonderful memory bandwidth, and could stream 64-bit data from and to memory at the clock speed of the CPU.
80MHz?
Re: How fast was the Cray?
Posted: Fri Sep 23, 2016 3:49 pm
by hgm
The one I calculated on (Cray Y-MP) was double that (167 MHz).
Re: How fast was the Cray?
Posted: Fri Sep 23, 2016 4:33 pm
by Laskos
hgm wrote:The one I calculated on (Cray Y-MP) was double that (167 MHz).
IIRC Cray Y-MP appeared in 1988 or so. The OP picture is from 1984, and I assumed they used Cray-1M or similar with 80MHz.
Re: How fast was the Cray?
Posted: Fri Sep 23, 2016 6:14 pm
by bob
Laskos wrote:hgm wrote:The Cray had wonderful memory bandwidth, and could stream 64-bit data from and to memory at the clock speed of the CPU.
80MHz?
The cray 1, yes. The machine used to win the 1983 WCCC was the first XMP-2 prototype, two cpus, 8.333 nanosecond clock speed, rather than the 12.5ns of the original Cray-1.
Re: How fast was the Cray?
Posted: Fri Sep 23, 2016 6:23 pm
by bob
hgm wrote:The one I calculated on (Cray Y-MP) was double that (167 MHz).
It ended up at a 6ns clock, although most were shipped at 6.1ns.
The T90 that I ran on in line 1994 I believe had a 2.1ns clock.
Their magic is in the vector hardware which can chain instructions so that the result of one instruction feeds directly into another instruction with zero latency and zero register traffic.
Re: How fast was the Cray?
Posted: Fri Sep 23, 2016 6:25 pm
by bob
Laskos wrote:hgm wrote:The one I calculated on (Cray Y-MP) was double that (167 MHz).
IIRC Cray Y-MP appeared in 1988 or so. The OP picture is from 1984, and I assumed they used Cray-1M or similar with 80MHz.
That photo was taken at the end of the 1983 WCCC event in NYC. We were, as I said, running on the Cray XMP prototype which was an 8ns machine with two cpus. In 1984 we won the ACM event running on the next version of this, the XMP-4 with 4 cpus. The YMP was the machine we used to win the 1986 WCCC event in Cologne, it had 8 cpus and a 6ns clock speed.
BTW THESE numbers I recall quite well.
For obvious reasons.
Re: How fast was the Cray?
Posted: Fri Sep 23, 2016 6:28 pm
by bob
BTW FF choked on that photo. That is Bert Gower on the far right, not Harry Nelson. I am not sure where Harry was when that was taken, he might have already left NYC to return to Lawrence-Livermore.
Ken is far left, Joe is next, then me and Bert on the far right.
