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Re: Do I need 64Bit if RAM is more than 4 GB?

On Wed, 2004-09-08 at 16:18 +0100, Paul Brook wrote:
> On Wednesday 08 September 2004 15:42, Ron Johnson wrote:
> > On Wed, 2004-09-08 at 15:03 +0100, Paul Brook wrote:
> > > On Wednesday 08 September 2004 14:45, Ron Johnson wrote:
> > > > In fact, it seems to me that *any* 32 bit processor (SPARC, HPPA,
> > > > Power) that wants to be able to use more than 4GB of total RAM
> > > > would have to use such a segmentation scheme.
> > >
> > > Err, all of the above have 64-bit variants.
> >
> > Yessss, but they didn't *start* with 64 bit variants.
> Actually Power did. It was designed as a 64-bit architecture that can also be 
> run/implemented with only 32-bits.

"Part IV: IBM RS/6000 POWER chips (1990). . . ."
"Thirty two 32-bit registers were defined for the POWER1 integer 
unit, which also included certain string operations, as well as 
all load/store operations."
Blah blah blah POWER2
"It was superceded by the POWER3 (Early 1998), with eight functional
units (two FPU, three integer (two single cycle, one multicycle),
two load/store, and branch unit), but capable of operating at much
higher clock speeds. In addition, a 64 bit version, the PowerPC 
A35 (Apache), was designed for the AS/400 E series"

So, the first 64 bit POWER chips arrived 8 years after the 32
bit versions.

> > >                                            I don't know if the
> > > 32-bit variants support more than 4GB ram, but I doubt it.
> >
> > Oh come on.  You think the SPARC32s, Powers & PA-RISCs that ran
> > big Solaris, AIX and HP-UX SMP boxen in big shops *never* had more
> > than 4GB of RAM?
> >
> > I find it supremely hard to believe that Intel is the only company
> > to have a 32 bit chip that can address more than 4GB of RAM.
> Well, sparc64 has been around an awful long time. Adding PAE-like hacks seems 

Since 1995.

> a strange decision when you have backwards compatible 64-bit CPUs.

There were largish SMP SPARC32 boxen for many years before the
SPARC64 came into existence.  I can't find any references on the
web, but some of those big boxen had to have more than 4GB RAM.
Ron Johnson, Jr.
Jefferson, LA USA
PGP Key ID 8834C06B

"Peace is a daily, a weekly, a monthly process, gradually
changing opinions, slowly eroding old barriers, quietly building
new structures."
John F Kennedy

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