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Article #2783Re: VERY LARGE main memories
From: Guy Harris
Date: Tue, 09 Sep 1986 18:18
Date: Tue, 09 Sep 1986 18:18
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3603 bytes
> Gawd, you guys on the net! Come on!
>
> So VAX/Unix oriented, so blinded!
Oh, come off it. You damn well know that most machines out there,
regardless of whether they run UNIX or are VAXes, are byte-oriented. The
use of "byte" when talking about memory sizes has *NO* relation *WHATSOEVER*
to a VAX or UNIX mindset.
> The Cray is a word oriented machine. Take out the factor of 8 from all
> of your calculations. You can tell a person's thinking by the words they
> choose. The Cray-2 is a 256 MW not a 2 GB machine. These are not the same
> because the conversion is non trivial.
Why? Does the Cray-2 store characters one per word? Does it store
*everything* one per word? Even if it does, that isn't enough to recommend
that "word" be used in a general discussion of large main memories. "word"
is a *useless* term for general discussions of memories, because it means a
different amount of memory on different machines. This discussion is NOT a
discussion of the Cray-2, it is a discussion of large main memories. As
such, the byte is the appropriate unit to discuss, since it is the same size
on almost all machines out there.
> Crays are word oriented machines.
You already said that. Merely stating this twice doesn't make it more
interesting. Explain *why* this renders discussion of Cray memory sizes in
bytes inappropriate. The PDP-10 is a word-oriented machine also; however, a
9-bit byte is a *very* appropriate unit for comparative discussions of
memory size, since one (9-bit) byte holds a character (which can be
addressed independently given a byte pointer), four bytes holds an integer,
(byte) pointer, or single-precision floating-point number, and eight bytes
holds a double-precision floating-point number - just like the VAX. The
available range of values of these types are different from that on a VAX,
but the difference is not enough to make a difference in gross discussions
of memory sizes.
> Anyone who says "2 GB" is showing a great deal of naive.
That's "naivete", modulo various diacritical marks, and this statement
needs a lot more defense than you've given it. If the problem is that a
given data structure (tree, 2D array of floating-point numbers, etc) takes a
different amount of memory on a Cray-2 than on another machine, then the
appropriate unit in the discussion is *NOT* words, it's elements of said
data structure.
> Get off your VAXen an try Univacs (36-bit), IBM's inverted bit order,
> and other systems.
"*BIT* order"? What relevance has that? I presume you meant "*byte* order,
in which case which "inverted byte order" do you mean? The byte order on
the IBM PC is the same as that on the VAX, and I could see some future
80386-based IBM machine having lots of main memory. The 360/370 family, by
the way, is byte-oriented and memory sizes are given in bytes....
Your assumption that the use of "bytes" in this discussion is an indication
of VAX/UNIX tunnel vision is way off the mark.
--
Guy Harris
{ihnp4, decvax, seismo, decwrl, ...}!sun!guy
guy@sun.com (or guy@sun.arpa)
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Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: arc1-ca.pugleaf.net!utzoo!mnetor!seismo!lll-crg!lll-lcc!pyramid!decwrl!sun!guy From: guy@sun.uucp (Guy Harris) Newsgroups: net.arch Subject: Re: VERY LARGE main memories Message-ID: <7078@sun.uucp> Date: Tue, 9-Sep-86 14:18:29 EDT Article-I.D.: sun.7078 Posted: Tue Sep 9 14:18:29 1986 Date-Received: Wed, 10-Sep-86 01:30:50 EDT References: <1645@ames.UUCP> Distribution: net Organization: Sun Microsystems, Inc. Lines: 61