Re: OT: Cache memory



On 2011-09-23 04.21, glen herrmannsfeldt wrote:
Rich Alderson<news@xxxxxxxxxxxxxxxxxxxxxxxx> wrote:
koehler@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx (Bob Koehler) writes:

PDP-10 implementations varied. But according to the hardware
architecture manual (it's been about 28 years since I read it)
the "accumulators" (address 0 - 20 octal) are memory addresses,
but are referenced so often that they are almost always in cache.

Only in late-model PDP-10 models. The PDP-6, KA-10, KI-10,
and original KL-10 processors do not have cache.

Depending on your definition of cache.

Some are considering the registers (in computer architecture terms)
cache for the low memory addresses.

Does:

MOVEM 0,1

run faster than

MOVEM 0,1000

? Can that be called a cache?

I would not call that cache. The fact that processor registers overmap some memory addresses does not make it a cache. A cache should be available for all memory, or else it's not cache, but just some faster memory.
You might as well ask yourself if you have cache if you have two memory boxes on the CPU, and one of them have faster memory than the other otherwise.

Johnny
.