I've heard that the address bus limits what a cpu can put out.  I find
this hard to believe since the cpu has ***millions*** of transistors
embedded in it.  I know that there aren't millions of tracers on the
motherboard.  So I say the person who says the address bus is the
greatest limitation on computer manufactures doesn't know what they're
talking about!  Surely a higher capacity address bus could be
installed if it was needed.  So what in the world is more of a
limitation on computer manufactures--address bus, cpu
capacities, memory mediums or some other component of the
***hardware***?  Please provide excerpts with links to the source
articles and any background information that you might have from your
own personal studies, if you can do it, which I highly doubt.  Please
be specific as to which component restricts manufacturers the most
(currently and over the long run). (yeah, right, like there's someone
here who can do THAT!)
Thanks.

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Request for Question Clarification by maniac-ga on 30 May 2004 18:10 PDT

Hello Musicandmore,

Hmm. An interesting question but a $2 answer (a single link or few)
will not do the question justice.

For example, I can describe the specifics of a shared memory interface
in a PC cluster where the current limitation of performance is the
speed of PCI bus (33 Mhz / 32 Bit) and where higher speed host bridge
chip sets do not work properly with the application.

In this case, faster CPU's won't help unless you get sufficient memory
to run the application in each node (and thus use fewer cluster
nodes). More memory won't help unless you get faster CPU's. The
current nodes would run faster with faster busses - but current 66 Mhz
/ 64 Bit PCI busses don't work right with the application.

There are several examples of tradeoff's such as these in computer
design. I you adjust the price offered, I could describe this one in
more detail or provide references to others for your use.

  --Maniac

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Clarification of Question by musicandmore-ga on 30 May 2004 19:52 PDT

Really, what I'm after is the single factor that limits the capability
of only the fastest computers.  I guess like the computers NASA and
the Dept. of Defense would use.  And also your typical user: in the
thousand dollar range of PCs (let's assume the consumer get's the best
bang for his buck) what's the single factor in their case?  (I mean,
if you really know)

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Request for Question Clarification by maniac-ga on 31 May 2004 07:45 PDT

Hello Musicandmore,

You won't find any one factor that is "most important". I recall an
old study (done back in the late 1970s) which compared the
 - Cray 1 (first vector processing machine)
 - CDC 7600
 - Illiac IV
the latter provided multiple processors. There were applications that
ran best on one machine and less well on the other two.

One machine had more memory - so large memory applications ran best on
it. [larger than the physical memory of the other two machines]
Vector processing was a key for some applications - the Cray was best for those.
One machine had better I/O performance so HUGE applications (those not
fitting into memory) ran better on it.

There is another more recent reference (2000) at
  http://www.flightgear.org/hardwarereq.html
describing using home PC's for flight simulators. Scroll down to the
message by Steve Baker which describes the overall approach used to
generate the display. If you have a slow CPU but a decent graphics
card, you still get good display performance - perhaps better bang for
the buck.

To get best performance on a home PC today, my general recommendation
at this time is to buy the most memory (RAM) you can afford with a
decent CPU. That appears to be the best cost tradeoff today.
  --Maniac

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Clarification of Question by musicandmore-ga on 31 May 2004 15:15 PDT

Well I didn't really expect that the question asked could be answered
in detail for the price offered, but I guess it comes down to
addressing limitations in general.  And it is usually the cpu, ram or
bus that determines those limitiations depending on the application. 
So the limitation depends on the application being used.  This doesn't
really answer my question, maniac, but since you took the bait i'll at
least pay you the 2 bucks (which I barely have) for your thoughtful
answers if you want.  Could you just comment on my interpretation of
the info you provided in your final answer if you choose to accept my
last 2 bucks (virtually)?  (It would be fair for me to give you the
two bucks)