20 Jul
2016
20 Jul
'16
3:28 p.m.
On 20/07/2016 20:29, Paul Koning wrote:
I don't remember the earlier ARM designs, but it
was my impression
that DEC's StrongARM was the one that made really large strides in
low power (especially power per MHz of clock speed). Interestingly
enough, StrongARM was one of the few (and the first?) independent
designs; it used the ARM architecture specification but not the
actual logic design as others did.
That's almost right. An ARM2 dissipates less than 2W (according to my
data sheet, but that's maximum allowed dissipation and I think typical
consumption is much less than 1W) with its normal 5V supply, averaging
some 6-8 MIPS with a 12MHZ clock. It's a 2micron CMOS process. The
original ARM used a 3micron process but was only used for testing and
development; I can't remember what ARM3 used but IIRC it was a lot
smaller though still the same core design, and it's certainly low power
(under 1W) despite having a lot more transistors (largely for cache) and
a higher clock speed.
StrongARM SA-110 uses roughly 450mW, but with Vcc around 1.75V it
claimed about 100 MIPS at 100MHz, in a 0.35micron process. It was a
collaboration between ARM and Digital, but AIUI the hardware design was
done mainly or perhaps completely by Digital. Yes, it was the first
independent design, as far as I know. Earliest designs were done by
Acorn and later I think by Acorn with VLSI, and ARM with Digital
(ARM6/7). I had access to early SA-110 development stuff for a project
in 1996 but I had to go to Digital to get it, not Acorn/ARM.
--
Pete