In sci.space.policy Rich <someone@somewhere.com> wrote:

And unlike modern computers, it doesn't have any cache memory.

Why would it need cache? The memory ran at full processor speed. Cache
is used to buffer things of vastly different speeds, like disk blocks

The memory certainly didn't run as fast as the processor, for that 
you would have needed to use a pipelined bus connected to a 0-latency,
ZBT SRAM at teh very least, somethingthat didn't even exist back then. 
You would have needed to clock it at 2x higher frequency than the core
too.

It didn't have amemory system that ran at the same *speed* as 
the processor, it had a memory system that ran at the same
frequency. The two were not the same even back then. Even
an instruction buffer that just did simple prefetch would have
sped it up. Go on, do the math if you want to argue otherwise.

for disk cache, and memory for processor cache. This is because the
modern processor runs 20x faster than the memory bus. Without the
cache the processor would spend most of it's time waiting for memory
access. With cache it runs at full speed for a large percentage of the
time, bur it still must wait for cache to fill whenever non-cached
memory is accessed.

The difference in frequency of the processor vs. that of memory system 
is irrelevant. What matters is the excution rate vs latency (and in 
limited cases bandwidth) of the memory system. 

Cache is not a good thing WRT computer speed. It's a sign that your
computer is running slower than it's processor.

If your memory runs faster than your processor in real terms you 
should fire your processor design team. Becuase they weren't trying
at all.

[snip]

You want to compare system speeds you need to check some benchmarks.
And even these can be fooled if the entire benchmark fits in cache.
Look at the difference a large cache makes for SETI, everything else
being equal. This is why streaming video skips and breaks on a modern
2GHZ celeron, only 128K of cache, the system is limited to memory
speed for most things.

latency problems in media display are probably caused by OS deficencies
not processor speed. 

Or better yet, compile the same code with the same compiler on both
machines. That would give a more reasonable comparison.

Rich

Alex.

-- 
	Sander

+++ Out of cheese error +++