Re: How many times must Apple make such DRASTIC architecture changes?

[Paul Schlyter <pausch@NOSPAMsaaf.se>]

In article <65z*EhOQq@news.chiark.greenend.org.uk>, 
timc@chiark.greenend.org.uk says...
>In article <11ah0pqdup2vq4c@corp.supernews.com>,
>Laine Houghton <laine@intergate.com> wrote:
>>
>>Aren't OS's being written and tested on the IA-64 and AMD 64 at this moment?
>
>64-bit OS's have been around for a long time,

For almost 30 years.  I believe the first 64-bit os was COS (Cray OS) for 
the Cray-1 supercomputer, released in 1976.  It definitely didn't have a
full 64-bit address space, but the hardware did have a 64-bit word size.
And it was word addressable - an individual octet(*) had to be accessed by 
reading the 64-bit word where it resided and then shift and mask it out.
The performance of the Cray-1 was approximately the same as a P-III running
at 500 MHz.  The Cray-1 performed better though if the parallell hardware
could be put to good use.  The actual clock frequency of the Cray-1 was 80 
MHz -- a lot back then, but "almost nothing" today.

This was the same year as when the Apple-1 was released.  So 64-bit OS'es
are as old as the Apple-1.

(*) I use the work "octet" rather than "byte" here, because at that time
byte sizes of something other than 8 bits was not uncommon.


>but not in the mainstream.
>DEC alias Digital alias Compaq alias HP created the Alpha back in the
>early 90s.  That has had a full 64-bit address space for years.
>
>As to the IA64, it actually has a 50 bit physical address space (I
>think).  I have an SGI Altix at work which has 192 GB of RAM, in a
>single operating system image, and which a single process can access in
>one go.  SGI have built much larger machines for some customers; I
>believe there is a *single* machine in Japan with 13 TB (yes, terabytes)
>of physical RAM.  The SGI cluster NASA are building is a cluster of
>larger Altixes, in terms of CPU count, but they don't have as much
>memory per node.
>
>As far as I know, no-one except SGI currently markets machines which can
>take as much RAM as this.  Compaq used to - our Altix' predecessor
>machine was an AlphaServer GS320, which also had 192 GB of RAM.
>
>Tim
>
>

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Paul Schlyter,  Grev Turegatan 40,  SE-114 38 Stockholm,  SWEDEN
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