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From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.unix.questions
Subject: Re: Vax processors
Message-ID: <7622@mimsy.UUCP>
Date: Tue, 21-Jul-87 00:42:44 EDT
Article-I.D.: mimsy.7622
Posted: Tue Jul 21 00:42:44 1987
Date-Received: Wed, 22-Jul-87 04:02:51 EDT
References: <138@bernina.UUCP> <13413@topaz.rutgers.edu>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 51
Keywords: Vax, CPU, Speed

In article <13413@topaz.rutgers.edu> ron@topaz.rutgers.edu
(Ron Natalie) writes:
>... The CPU in the 750 was about a third the speed of the 780.

Ron, you should know better than that.  The 780 is usually rated
at 1 MIPS; the 750 is typically called about .6 or .7 MIPS, not .3.
It is not *that* much slower.  (But any slower is too much slower!)

>... One other CPU, the 730, was also available, this was again
>a third as slow as the 750 and was hence pretty unusable

The 730 is about .3 VAX MIPS, I understand.

>The 785 is essentially a fast CPU upgrade for the 780 CPU ...

running at a nominal 1.5 VAX MIPS.

>The 8600 is one of the new VAX products.

Not all that new.

>The bus changed again (now called BI)

No, the BI machines are the 8200/8300/8500/8700/8800 series.  I
could never keep the details straight, but some of them are multiple
CPU systems.  The 8600 uses its own internal bus (the `A' bus) and
has bus adapters.  The only adapters available now are SBIAs, which
present 780-style SBI interfaces.  One can then plug in 780 Unibus
adapters or Massbuss adapters or whatever.  From the 4.3BSD kernel
code, it is apparent that DEC could come out with new IO adapters
(perhaps a BI adapter a la the 8800's DB88?).

The 8600 is rated about 4 VAX MIPS; the 8650 (a `tweaked' 8600) is
about 6 VAX MIPS.  Rumour has it that, using properly hand-selected
and tuned up boards, one can push the clock all the way up to where
an 8600-series machine runs at 12 MIPS.  I wonder how long it will
take for DEC to come out with the 8675. . . .

We have an 8250.  This is supposedly rated around 1.2 or 1.3 VAX
MIPS.  It is hard to tell whether this `feels right', as yet:  We
were supposed to get Ultrix and a boot RX50 with the machine, but
we did not, so I borrowed an Ultrix 2.0 field test tape and managed
to boot it from a TU80.  The field test kernel will not build, and
the generic kernel's TCP or BVPNI Ethernet driver does not work
(hard to tell which); and the machine crashes under any sort of
load anyway.  After much of hacking on my part, 4.3BSD finally
boots, then promptly crashes (right after mapping the BUA I/O and
register space ... very strange).
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7690)
Domain:	chris@mimsy.umd.edu	Path:	seismo!mimsy!chris