
First Programmable Memristor Computer - headalgorithm
https://spectrum.ieee.org/tech-talk/semiconductors/processors/first-programmable-memristor-computer
======
peterlk
Are memristors real? I feel like I've been hearing about how memristors are
going to revolutionize computing for as long as I've been paying attention
(~10 years). And yet, they never arrive. I also recall some detractors who say
it's all marketing and "true" memristors aren't going to be viable for a super
long time. Can anyone from HN summarize what the deal with memristors is?

~~~
p1esk
I work on memristor based crossbars for neural network computation. Memristors
are real, but we’re pretty far away from mass scale commercial products.

~~~
touristtam
Any recent article recommendation? :)

~~~
p1esk
[https://www.ece.ucsb.edu/~strukov/papers/2018/natcommMLP2018...](https://www.ece.ucsb.edu/~strukov/papers/2018/natcommMLP2018.pdf)

------
throwawaycert
Obligatory reminder that "memristor" is mostly a marketing hype word at this
point. No clear example of the original memristor hypothesis has ever been
crafted, and there is wide disagreement on what should or shouldn't be called
a memristor, and it's not even agreed whether a memristor can physically exist
_at all_. And hearing about the "first" memristor <whatever> is basically a
biannual occurrence.

Also, reminder that even if someone manages to make a real memristor and
everyone agrees it is a memristor, it may not end up being a big deal. They
have some nice hypothetical properties, but they're not magic, and any
widespread use would probably take decades.

~~~
peterlk
What is "the original memristor hypothesis"?

What definitions of memristors would make them physically impossible?

What hypothetical benefits are so compelling about the physically possible
definitions?

~~~
throwawaycert
In the 60s/70s, an EE/CS guy named Leon Chua did some clever math that
suggested we could build transistor-like devices that had a non-linear
relationship between charge and flux and called it a memristor. He didn't
build one, and as far as I know it's not something he's spent all that much
time on since.

In the 90s somebody at HP must have mentioned memristors in hearing range of
their marketing department and suddenly HP was going to have a product to
market in a few years.

Yeah. Never happened. Nobody's done it.

In theory, such a device could allow us to do things like build extremely low
power non-volatile memory (a flash replacement, basically). A lot of marketing
hype has talked about completely replacing computer RAM with non-volatile
memristor-backed memory, but again, neither it nor anything like it has
happened. But as it turns out, battery-backed DRAM covers a multitude of sins
anyway.

The actual debate over physical possibility is because it's _too_ low-power,
to the point that an actual implementation might violate lower theoretical
limits on the amount of energy required to change the state of a bit. In other
words, it might violate the second law of thermodynamics, which is something
of a problem.

~~~
aperrien
Yes, memristors are real, and no, their properties are not magic[1]. As I
stated elsewhere on this thread, you can even make them at home[2]. It's even
been discussed here on Hacker News before[3].

[1]
[https://electronics.stackexchange.com/questions/76097/what-a...](https://electronics.stackexchange.com/questions/76097/what-
are-the-characteristics-of-a-memristor)

[2]
[http://sparkbangbuzz.com/memristor/memristor.htm](http://sparkbangbuzz.com/memristor/memristor.htm)

[3]
[https://news.ycombinator.com/item?id=9853984](https://news.ycombinator.com/item?id=9853984)

~~~
throwawaycert
They are real if you accept the branding of of companies trying to sell
products that don’t really do much to people who are lured in by buzzwords.
Those of us who actually do real work have serious doubts.

------
justinmchase
> Arrays of memristors can do these tasks efficiently because they become
> analog computations instead of digital.

What does this even mean in a computer? How can you do a non-digital
computation?

~~~
Balgair
Bit depth becomes continious, essentially. Instead of a 32 bit number, you
just have any number you please, as it's continuous. Granted, there _are_
restrictions in translating this to memristors, but thats essentially the
gist.

The real key feature of memristors is not the math or any of that stuff, it's
that all that math is stable under power cycling and it take nearly no power
to compute things. The article mentions that they preformed 188 GigaFlops with
about 0.3W of power. The human brain is about 20W at about 1 ExaFlop (a VERY
coarse estimate) for comparison.

This power savings opens up the doors for very good computation (ML stuff) on
very tiny power sources.

~~~
heavenlyblue
How’s that “bit depth” different from the bit debth you get when you implement
a simple analog summing circuit?

~~~
rusticpenn
The number of elements required is much less.

~~~
Balgair
The 'standard' summing circuit [0] typically requires an op-amp, which is in
itself a multi-element component, and a few resistors. With a memristor, you
can theoretically skip the op-amp and just use the passive elements, though an
op-amp is likely still needed to read out the very small signals [1].

[0] there are MANY ways to skin this cat, but here is a simple one:
[https://www.electronics-tutorials.ws/wp-
content/uploads/2013...](https://www.electronics-tutorials.ws/wp-
content/uploads/2013/08/opamp11.gif?fit=457%2C223)

[1]
[https://image.slidesharecdn.com/1205-141021211518-conversion...](https://image.slidesharecdn.com/1205-141021211518-conversion-
gate01/95/proposals-for-memristor-crossbar-design-and-
applications-11-638.jpg?cb=1413926248)

~~~
rusticpenn
The opamp is mainly needed of impedence matching. There are several ways to
contruct such circuits using just inverters.

