16 Dec
2015
16 Dec
'15
4:19 p.m.
On 14 December 2015 at 23:16, Ian S. King <isking at uw.edu> wrote:
And think of all the PDP-8s *still* buried in the
control units of
factories across the world. The majority of these machines had no
displays, not even teleprinters. Some had custom controls wired in through
stock or custom modules, and some had no more "UI" than the front panel
("set switches 2 and 3 to the 'on' position and press the 'run'
key").
Some didn't even have that - the stock 8/m was a turnkey system. The
reasoning was the same as that behind the microcontroller replacing the
555: complex behavior could be modeled in software rather than intricate
analog elements, and it was easy to change things if you needed to (e.g.,
if you changed out an instrument or effector.
Much the same reason that ARM cores are widely embedded today. AIUI
it, it is typical for a modern smartphone not merely to be based on a
multicore ARM CPU, but to contain something ITRO half a dozen other
ARM cores as well.
The main CPU may well be a big.LITTLE device -- e.g. 8 cores, 4
complex superscalar fast ones which take lots of electricity, and 4
small simple dumber ones *with the same instruction set* that use very
little but have a much lower IPC, so that the phone's OS can switch
between fast cores and power-frugal cores depending on load and
available battery power.
Then the Wifi chip contains an ARM core running part of the stack, and
so does the Bluetooth chip, and so does the NFC chip, and so does the
power-management chip, and so does the battery-monitoring chip, and so
does the USB controller... etc.
ARM cores can be *very* cheap to license, and it's easier to implement
stuff in software and run it on a tiny slow ARM core than build
hardware to do it.
By the same token, a colleague and friend of mine recently discovered
this gem & Tweeted it:
Chris Williams ?@diodesign
TIL modern Intel chipsets have a hidden SPARC core (inside Intel's
Management Engine)
https://recon.cx/2014/slides/Recon%202014%20Skochinsky.pdf ? (2014)
2:59 AM - 14 Dec 2015
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