On 21/07/2016 13:38, Liam Proven wrote:
On 20 July 2016 at 21:29, Paul Koning <paulkon...@comcast.net>
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
Hmm. That wasn't my impression at the time, no.
The big deal with StrongARM was that it had a dramatically increased
speed -- whereas Acorn ARMs ran from 8MHz in my original Archimedes
A305 to 12MHz for the first SoC ones (A3010 with ARM 250) to 25MHz
for the ARM3-powered A5000, Digital's first StrongARM ran at
100-200MHz. To keep the core fed with data at this ridiculous speed,
it had onboard L1 instruction & data caches.
So at least in the marketing to the Acorn user community, no, power
draw wasn't even mentioned. It never came up. The original ARMs were
low-power, and so was StrongARM.
Yes and no. StrongARM was even lower power as well as faster. If
you're suggesting that that's just evolution due to things like reduced
process size, I possibly agree. But a StrongARM has many times as many
transistors as an ARM3 (for example) let alone an ARM2, and initially
ran 3 times as fast (100MHz vs 33MHz - the earliest ARM3s were 20MHz,
but production runs were 25MHz and later 33MHz, and eventually SA-110
ran to over 200MHz) yet uses less power. I don't have the data sheets
for ARM6 and ARM7 so I can't compare, though.
As for the marketing, I recently came across an Acorn press release
announcing ARM, in which Sam Wauchope (CEO) was quoted saying it
delivered 100MIPS per watt, so power was indeed a selling point. I
worked for Sam at the time[1], so I remember that. OK that's for one of
the Acorn ARM chips, not StrongARM, but the point is still made. Not
all the marketing was directed at the Acorn community.
[1] and I still have my Archimedes A310 Serial No. 0000002 (and the box
with all the bits and pieces :-)) as well as my A410 and R260, both from
the first batches. I wish I'd kept an A500, though. All I have now is
the podule to connect it to a Beeb. Anybody got the machine to put it in?
--
Pete
Pete Turnbull
