[Gllug] Laptops?

[Rich Walker]

Richard Jones <rich at annexia.org> writes:

> On Wed, Oct 29, 2003 at 08:53:39PM +0000, Rich Walker wrote:
>> http://www3.sk.sympatico.ca/jbayko/cpu5.html
>
> Thanks Rich. That's a really interesting page. I hope you don't mind
> if I ask you another question (since you seem to know what you're
> talking about!)

Well, i try...

> The POWER architecture as described appears to be a 32 bit
> architecture. Or at least, the data registers are described as 32
> bit. Then the PowerPC 620 is described as extending the architecture
> to 64 bits. Does this mean that the G4 is a true 64 bit processor?

Good question. Was there a huge Apple marketing campaign on this,
because I'm sure there would have been...

Looking again at the documement cited, the 620 had 64-bits, but the only
part of the design that got re-used was the backside bus (to an offboard
L2 cache).

> What about the OS - do compilers for the Mac have 64 bit 'long', large
> virtual address space, and so on? (The reason I ask is that I'm also
> the proud owner of a Sun Ultra 5, running Debian, but I still haven't
> managed to compile a 64 bit program on this machine. The compiler
> seems to remain resolutely 32 bit, which is disappointing).

I'd expect that they're struggling to deal with this now :->

The results from the Alpha architecture suggest that fully-64-bit code
(long=64 bits, pointers=64-bits) suffers a significant space penalty
which translates into a 5% slowdown. Hence most systems use 32-bit pointers
unless they need all 64-bits of pointer.

cheers, Rich.

>
> Rich.
>
> ObMusing: Back in the day I actually saw the original IBM POWERStation
> (I think it was called - original POWER 1 in 4 or 5 chips). It looked
> like an old IBM PC XT, but literally scaled up by about 30% in every
> direction. This was at an interview at a university, so I asked the
> lecturer what he used it for. He said it was basically given to the
> university, and spent most of its time turned off. This was, like, 20
> grand's worth of kit ...
>
> -- 
> Richard Jones. http://www.annexia.org/ http://freshmeat.net/users/rwmj
> Merjis Ltd. http://www.merjis.com/ - all your business data are belong to you.
> 'There is a joke about American engineers and French engineers. The
> American team brings a prototype to the French team. The French team's
> response is: "Well, it works fine in practice; but how will it hold up
> in theory?"'
>
> -- 
> Gllug mailing list  -  Gllug at linux.co.uk
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-- 
rich walker         |  Shadow Robot Company | rw at shadow.org.uk
technical director     251 Liverpool Road   |
need a Hand?           London  N1 1LX       | +UK 20 7700 2487
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