6 Feb
2013
6 Feb
'13
12:12 p.m.
From: Eric Smith
Sent: Wednesday, February 06, 2013 2:04 AM
Rich Alderson wrote:
> Computer Interconnect (CI) was a 50Mbit
ethernet[1]
70 Mbps.
Not originally. That was the HSC70 upgrade, which was VAX only.
Although it clearly was inspired by Ethernet, it is
dissimilar enough
that I'm not sure I'd even call it a (lower-case "l") ethernet.
It's similar enough that I would.
> designed for the
> Jupiter (follow-on to the DEC-20, to be called the DECSYSTEM-4050),
> and later retrofitted to the VAX,
Perhaps you have more information about CI history
than I do, but the
documents I've seen suggest that it was intended for everything from the
KL and VAX-11/780 up. The case could be made that it was "retrofitted"
to the VAX-11/750. The original CI hardware, including the PLI
interface, was clearly designed to be suitable for machines with memory
bandwidth as low as that of the VAX-11/780.
When I first heard about the CI, it was in a Jupiter dog-and-pony that DEC
did for us at UChicago. CI was touted as new for the Jupiter, and there
was no indication that it would be retrofitted to older 36-bit systems.
That was in 1982.
When TOPS-20 v6 was field-tested at Stanford, the Digital muffins were all
excited because the CI had been made available for the KL processors in
spite of the 1983 cancellation of Jupiter.
That was in 1986.
I think that any documentation from Digital which suggests that the CI was
intended for anything other than the Jupiter is revisionism in extremis.
Just my observations, of course. YMMV. OIMACTTA. And all that.
Rich Alderson
Vintage Computing Sr. Systems Engineer
Vulcan, Inc.
505 5th Avenue S, Suite 900
Seattle, WA 98104
mailto:RichA at vulcan.com
mailto:RichA at LivingComputerMuseum.org
http://www.LivingComputerMuseum.org/