
AI revives in-memory processors - mindcrime
https://www.eetimes.com/document.asp?doc_id=1333238
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nabla9
David Patterson (who else) experimented with the idea almost 20 years ago.
Idea was to put CPU into SRAM, remove caches and connect to the rest of the
world with fast serial interfaces.

[http://iram.cs.berkeley.edu/](http://iram.cs.berkeley.edu/)

I'm guessing that mixing CMOS and SRAM into same process is hard to do in
large scale.

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jacquesm
SRAM can be CMOS.

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nabla9
Of course, I had a brain fart.

I meant mixing CMOS and DRAM.

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jacquesm
Ah, now I get it. I was wondering whether you meant to write that. Thank you
for clearing that up!

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tbrownaw
_aims to compute neural-network jobs inside a flash memory array, working in
the analog domain to slash power consumption._

That’s a bit more than just locating the processor inside the memory array.

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tathougies
An in memory processor is not simply a processor in a memory array. It's more
like a processor based on cellular automata where each memory cell also
performs computation.

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tbrownaw
Not sure how state machines / cellular automata tie in to analog processing.
Am I missing something, or is the article mixing things up?

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mywittyname
My thinking is that analog signals are a more natural and effective processing
medium for hardware neural nets. The "memory" component of the chip might be
constant signals representing the weight of each (initial) connection in the
network, which amplifies the down-stream signal.

Contrast this with digital circuits where the amplification of each transistor
is a high/low signal from an upstream transistor which represents a 0/1,
making it a switch.

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Quequau
Whatever happened to that tech that Micron was working on? Automata processors
or something.

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joe_the_user
Sounds exciting and uncertain.

Questions: How close would this be to a drop-in replacement for a GPU? How
close could this sort of chip be to a general purpose SIMD[1] processor?

[1] [https://en.wikipedia.org/wiki/SIMD](https://en.wikipedia.org/wiki/SIMD)

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sanxiyn
Currently, PIM(Processing In Memory) has no reasonable programming model.
Hardware people don't seem to understand that without programming model,
hardware capability will remain unused. As long as this is not solved, PIM
will continue to fail.

The most reasonable one I have seen is Ambit from Microsoft Research. Ambit
looks nice for its proposed workloads, but it is still unclear how it can be
extended to more general computation.

[https://www.microsoft.com/en-
us/research/publication/ambit-m...](https://www.microsoft.com/en-
us/research/publication/ambit-memory-accelerator-bulk-bitwise-operations-
using-commodity-dram-technology/)

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jacobush
I think there is. Verilog and VHDL. A lot of "normal" programmers would
hesitate to call that "reasonable", I guesss, but if the shoe fits...

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sanxiyn
Well, joe_the_user asked for "drop-in replacement" for GPU or SIMD. Verilog
and VHDL are definitely not.

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joe_the_user
That's true but I'm also curious about what we would wind-up with with in-
memory processors.

Is it possible that the now-defunct Micron Automaton Processor would be an
example of the kind of model one would wind-up with?

It is still supposedly being studies here:

[https://engineering.virginia.edu/center-automata-
processing-...](https://engineering.virginia.edu/center-automata-processing-
cap)

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rasz
we had Ram based cellular automata for ~10 years now, didnt go anywhere

[http://www.micronautomata.com/research](http://www.micronautomata.com/research)

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sp332
Now we have a much more lucrative application for them.

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partycoder
There is a no discernible distinction between memory and computing elements in
nervous systems.

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ouid
extraordinary claims require more than zero evidence

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eleitl
Neuroscience 101.

