VAX (Was: Cromemco landmarks) - test-drb@ccmp.vtda.org

11 Nov 2001

Carlos,

Both have the FPU.  It was optional only in the sense that it was not
required for a minimal cpu.

Allison

-----Original Message-----
From: Carlos Murillo &lt;cmurillo(a)emtelsa.multi.net.co&gt;
To: classiccmp(a)classiccmp.org &lt;classiccmp(a)classiccmp.org&gt;
Date: Sunday, November 11, 2001 11:16 PM
Subject: Re: VAX (Was: Cromemco landmarks)

...
 At 03:02 AM 11/12/01 +0100, Iggy wrote:
>Carlos Murillo skrev:
>>Didn't the uVax II implement some of the original VAX instructions
>>with emulation? I always wondered what the VUP rating would have
>>been were they not emulated.
>
>in order to reduce the architecture to a single (integer) chip, only 175 of
...
  the 304
instructions (and 6 of 14 native data types) were implemented (through
 microcode), while the rest were emulated - this
subset included 98% of
instructions in a typical program. The optional FPU implemented 70
instructions and 3 VAX data types, which was another 1.7% of VAX instructions.
 All remaining VAX instructions were only used 0.2%
of the time, and this
allowed MicroVAX designs to eventually exceed the speed of full VAX
implementations 
Aha! So, if I were doing numerical linear algebra in a uVaxII w/o the optional
...
 FPU, I could expect performance to be badly hit with
respect to the 0.9 VUP
rating.

(FYI, I always tend to benchmark machines using float performance,
because that's the kind of thing that I do for a living. I look at integer
performance only as something that has an impact on sparse linear algebra
blocks, as opposed to dense system methods).

How do I know if my Vaxstation 2000 has the optional FPU?  What is
its model number?

What about the Vaxstation 4000/60? Does it have a built-in FPU?

carlos.

--------------------------------------------------------------
Carlos E. Murillo-Sanchez   carlos_murillo(a)nospammers.ieee.org