21 Jul
2016
21 Jul
'16
6:24 a.m.
On 21/07/2016 13:38, Liam Proven wrote:
On 20 July 2016 at 21:29, Paul Koning <paulkoning
at 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