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From: omondi@unc.UUCP (Amos Omondi)
Newsgroups: net.arch
Subject: Re: Why Virtual Memory
Message-ID: <405@unc.unc.UUCP>
Date: Sat, 26-Oct-85 20:47:13 EST
Article-I.D.: unc.405
Posted: Sat Oct 26 20:47:13 1985
Date-Received: Mon, 28-Oct-85 03:29:27 EST
References: <480@seismo.CSS.GOV> <384@unc.unc.UUCP>
Organization: CS Dept, U. of N. Carolina, Chapel Hill
Lines: 21

> 
> It is interesting to note that 10 years ago or so, all large systems
> had virtual memory whereas small systems did not.
> 
> Now the largest systems (e.g., Cray 2) do not have virtual memory,
> whereas it is more and more common for small systems ("microprocessors", 
> and I use the term in quotes) to have virtual memory.
> 
> I wonder if in another ten years the "small" systems won't have
> virtual memory, but the "large" (i.e., gigantic) systems will again?
> 
> The "wheel of reincarnation" turns ....
> 


In taking the Cray 2 as an example, one should take historical, philosophical
, etc. considerations into account. The CDC 6600, CDC 7600, CRAY 1, and
CRAY 2 do not have virtual memory; and Seymour Cray was largely responsible
for their designs. Other CDC machines, inculding the Cyber 200 series which
are the in Cray1-Cray2 perfomance range, have virtual memory as do several
of the new Japanese supercomputers .