[geeks] Ultra 20 thoughts

[Charles Shannon Hendrix]

Mon, 04 Jul 2005 @ 12:25 -0400, Kurt Huhn said:

> I was really only responding the fact that Sun is selling a
> bog-standard peecee and charging a premium for their nameplate and
> (admitedly attractive) case.  The fact that, no matter what crap you
> add on to it, a peecee is still a peecee, is what I was getting at.

OK.  I was hoping it would be more than just a PC, and at least have a
decent BIOS and good build quality.

If not, then there isn't much point to it then.

> > The modern PC looks more like an Apple than a PC/AT, except for that
> > horrible BIOS.
>
>
> Not quite, man.  You should really look at the major differences
> there.  The Apple G5 is quite dissimilar from PC in terms of
> architecture.

I didn't say they were not different.  The PC is still a lot more like
an Apple than it is like a PC/AT.  

If you'll take a look at AMD64 systems you find pretty close.  That's
probably unfair, but that's what drives the industry right now and is
primarily what I'm talking about.  The Apple G5 is nicer but they aren't
all that different.

Both Apple G5 and the AMD64 PCs use HyperTransport to connect graphics
and I/O.  The Apple also uses it for memory and SMP.  The AMD64 uses a
seperate memory bus, and seperate HT links for SMP, up to 8-way SMP.

HT is built into the AMD CPU, while the Apple uses an HT host they call
the system controller.  If you read Apple's website, they act like
point-to-point I/O is something they created, but all HT systems have
this: it is a basic feature and requirement.  HT was invented by AMD.

If you look at how data flows, Apple has a faster CPU->HT link, but at
the same time must use it for everything, while the AMD has seperate
channels for memory, I/O, and SMP.

Different implementation, but same basic idea and benefits.

On an AMD64, the northbridge doesn't even do anything.  It's really just
a HT->AGP interface now.

External I/O is different.  The Apple G5 has a HT link to a PCI-X
controller, and all external I/O is done there.  It's a lot simpler and
cleaner, but does have the drawback of all external I/O sitting on a
single shared PCI bus.

The AMD64 uses a HT linked southbridge to control super I/O, PCI, and
things like SATA.  This is better than earlier designs, but still has
the complexity of the southbridge, and some southbridges go out of their
way to suck.

It really isn't necessary, since PCI and other devices can sit on HT,
but you have to put super I/O somewhere for compatibility with Windows.

BSD and Linux systems could run without it, but until Microsoft changes
their HAL, you can't totally get rid of the southbridge.

However, before long most AMD64 PCs will be seperating that on an HT
point, with PCI and other I/O sitting directly on HT.  It will at least
minimize the pain.

Intel is another story... they are pushing PCI-E for everything,
including areas where HT is superior.  I suppose it is mostly political,
since HT is an AMD technology.

> > There is no reason for most of the PC legacy hardware to exist in
> > emulation, it's a largely artificial requirement, and that includes
> > the stupid BIOS.
> >
> 
> Bingo.  Never mind the processors....

Well, there are PC motherboards with non-intel CPUs.  They just can't
get any market traction.

In any case, the legacy support 

to be limited to Intel CPUs either...

It's all marketing limitations, not technical limitations.

I also think that people might be more keen to get better systems than
the industry seems to think.  They might not know how to express it, but
they do have their frustations with current systems.




-- 
shannon "AT" widomaker.com -- ["The grieving lords take ship.  With these
our very souls pass overseas." -- Exile]