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From: mangler@cit-vax.UUCP
Newsgroups: comp.unix.questions
Subject: Re: Vax processors
Message-ID: <3426@cit-vax.Caltech.Edu>
Date: Sat, 1-Aug-87 03:01:22 EDT
Article-I.D.: cit-vax.3426
Posted: Sat Aug  1 03:01:22 1987
Date-Received: Sun, 2-Aug-87 11:24:42 EDT
References: <138@bernina.UUCP> <13413@topaz.rutgers.edu> <463@mtxinu.UUCP>
Organization: California Institute of Technology
Lines: 25
Keywords: Vax, CPU, Speed
Summary: BI machines

In article <463@mtxinu.UUCP>, ed@mtxinu.UUCP (Ed Gould) writes:
> (The 8x50 machines are faster versions of the 8x00's, but are otherwise the
> same.)

According to the February 1987 "Digital Technical Journal", the 8500,
8550, 8700, and 8800 all use the same CPU (with different microcode).
The 8800 is a dual 8700.

I understand that the 8200/8250/8300/8350 series is based on a 7-chip
implementation of the VAX-780, which was originally intended to be the
the Microvax, but when it became clear how much longer it would take,
they started on a one-chip subset design, and the latter project was
completed first.  (Does anyone know where the CVAX fits into this?)

Rumor also has it that the 750 was intended as the first VAX, but DEC
had so much trouble with the 750's LS-TTL gate-array design that they
ended up selling the engineering prototype (the 780) as a product.

Is there any truth to the legend that the designer of the 750's FPA
did such a great job that it outran the 780 at floating point, and
Marketing forced him to divide the clock by two?  Where is the
jumper?  (Most 750 timings seem to be multiples of 320ns, except a
few, like writes, that are multiples of 160ns - is this related?)

Don Speck   speck@vlsi.caltech.edu  {ll-xn,rutgers,amdahl}!cit-vax!speck