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From: stevem@f40.inmos.co.uk (Steve Maudsley)
Newsgroups: comp.arch
Subject: Re: 64 bits
Message-ID: <9660@ganymede.inmos.co.uk>
Date: 16 Aug 90 10:10:54 GMT
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In <40713@mips.mips.COM> John Mashey discusses some of the issues of space
relating to DRAM. 

To support his premise that big word-size machines will be in common
use, I would like to pass on a few observations about the 
semiconductor industry

	1. It takes about 10 years for a new manufacturing technique to 
	  become used in production from the time that the proof-of-concept
	  has occured in the labs. Hence, we can identify now the techniques
	  that will be in use in 10 years time.

	2. With a judicious use of imagination, there are now a sufficient set
	  of techniques availible to produce 1GBit monolithic DRAMs in 2000.
          These chips will be only about twice as large as current generation
	  DRAMs and that only to get the signal wires out.

	3. In volume production, all DRAM technologies cost the same amount
	  per chip (in dollars), regardless of the generation.

This nebulous set of observations implies that a 16Gbyte machine will have the
same memory cost as a current generation 64Mbyte machine, which we now commonly
use as NFS or X servers and consider an acceptable cost. NOTE: this is real
memory, not virtual memory which is typically 10 times bigger because with 
current technologies it is 10 times cheaper. Therefore, machines with 160Gbyte
of address space will be affordable.

You will need more than 32bits address space for these machines.

I haven't addressed the issue of what you do with it, but certainly we will be
using machines this size for simulating the logic circuits that we will be 
building with the same technologies, because that problem has to be sized to
the number of transistors that we can manufacture.

Stephen