🚀 go-pugleaf

Ian Watson (watson@cs.man.ac.uk) wrote:
: In article <44sl81$hr1@murrow.corp.sgi.com>, mash@mash.engr.sgi.com (John R. Mashey) writes:
: >In article <44p44b$aqe@news.dtc.hp.com>, shoens@hpl.hp.com (Kurt Shoens) writes:
: >|> Organization: Hewlett-Packard
: >|> 
: >|> Or another way to look at is economically.  Suppose in the future memory
: >|> system prices drop to 1 cent per megabyte.  Then 64 bits worth of physical
: >|> memory costs $160 billion.  Carrying it further, at .01 cents/megabyte it's
: >|> still $1.6 billion.
: >|> 
: >True ... but easily confusing.  I doubt that anybody intends to build
: >2**64 byte memories any time soon, hence the cost of such things is meaningless.
: >

: I don't know whether anyone has done this sum and I have missed it. If you
: assume indexing through memory at 1 nsec intervals, 32 bits of address space
: takes just over 4 seconds. 64 bits of space takes over 500 years!

: I have a feeling that for most of us, it could be a bit of a waste of money!

It sounds as though everyone is agreeing with each other.  We can't have 
that in this news group.  Allow me to supply an opposing point of view.

There are two reasons for increasing your bus size.
	1.  To address more memory
	2.  To increase throughput (bandwidth).

Very few people (who I know anyway) buy 64 bit machines to address more 
than 4GB of memory.  They do it to get faster throughput.  The extra 
address space is simply a side-effect.  While increasing your bus from 32 
to 64 bits may increase your address space by an enormous amount, it only 
increases the throughput by a factor of 2.  I can easily imagine users 
(in the next few years) wanting 128 bit graphics cards, disk controllers 
and network interface cards and thus wanting a 128 bit bus.

There!  That should start an argument.

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Michael Smith                                       msmith@mpx.com.au
                     
Emmenjay Consulting 
    Making computers work for you, not the other way around.

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