
Not Your Father’s Analog Computer - sohkamyung
https://spectrum.ieee.org/computing/hardware/not-your-fathers-analog-computer
======
emmelaich
(bit of history on that Tide Prediction Machine)

You can read the paper underlying the mathematics of tidal computation
including pictures and description here:

Special Publication No. 98: Manual of Harmonic Analysis and Prediction of
Tides (1940)

[https://tidesandcurrents.noaa.gov/publications/SpecialPubNo9...](https://tidesandcurrents.noaa.gov/publications/SpecialPubNo98.pdf)

I worked on a Fortran program which I'm pretty sure is the direct descendant
of this paper and the analog computer.

It originated in 1967 and was still used in the mid 1990s. And probably still
is used.

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Animats
One of the best analog computers still in use is the F-16's flight control
system. Later F-16s use a digital system, but the classic quadruple-redundant
analog computer is still in use. Very 1970s electronics.[1]

[1] [https://duotechservices.com/pitch-1-board-repair-of-the-
anal...](https://duotechservices.com/pitch-1-board-repair-of-the-analog-flcc)

~~~
AnkhMorporkian
I would have to assume that it's not still in use by the US, lest this be
incredibly classified, correct?

~~~
jacquesm
F16's fly for many countries.

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Pulcinella
The Omega Tau podcast discusses analog computers on episode 159. It’s probably
one of my favorites.

[http://omegataupodcast.net/159-analog-
computers/](http://omegataupodcast.net/159-analog-computers/)

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nickpsecurity
Prior links of mine on general-purpose analog, analog accelerators, and/or
neural analog:

[https://news.ycombinator.com/item?id=11731697](https://news.ycombinator.com/item?id=11731697)

[https://www.schneier.com/blog/archives/2015/07/friday_squid_...](https://www.schneier.com/blog/archives/2015/07/friday_squid_bl_488.html#c6701962)

~~~
mindcrime
Also, while it's somewhat slow traffic-wise, there is an analogcomputing sub
on reddit.

[https://www.reddit.com/r/analogcomputing/](https://www.reddit.com/r/analogcomputing/)

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aidenn0
Since they are doing dedicated hardware anyways, I'd like to see it compared
to custom 6-bit digital circuit designed for the same calculations; I expect
the power consumption would be much closer to the analog computer.

~~~
TuringTest
If a generic programmable analog computer -like the one described in the
article- can have power consumption similar to a custom-made digital circuit,
you are still gaining something.

~~~
aidenn0
I said "designed for the same calculations" so it should be as generic as the
analog one. The analog computer described in the article is distinct from
general purpose compute units, as it performs calculations in a pipeline.

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th0ma5
There's always room for Jell-O (as an analog computer)
[http://hplusmagazine.com/2014/01/10/defend-your-network-
with...](http://hplusmagazine.com/2014/01/10/defend-your-network-with-a-
bucket-of-jell-o/)

------
keithpeter
An example from the UK

[http://blog.liverpoolmuseums.org.uk/2015/08/tide-
predicting-...](http://blog.liverpoolmuseums.org.uk/2015/08/tide-predicting-
machines-restored-and-re-displayed/)

~~~
theoh
Kelvin invented the concept: [https://en.wikipedia.org/wiki/Tide-
predicting_machine](https://en.wikipedia.org/wiki/Tide-predicting_machine)

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mechatronix00
Is there a FPGA equivalent for these analog chips? I'm guessing no but that
would be handy to have field programmable analog computers.

~~~
ChuckMcM
I haven't seen any but what you would really need would be a challenge to put
into a chip. Essentially you would want a wiring matrix of that you could use
to connect groups of integrator / differentiator units to, and then switchable
resistors and capacitors to set rates. Not as straight forward as one might
like.

An alternative might be a matrix of DSP 'cores', instead of switching an
analog signal around you would move around an I/Q stream. That might be an
interesting path to wander down for a bit.

~~~
junkcollector
A voltage controlled varactor can be made from 2 non-complimentary mosfets
with a common body bias. The differential amplifier can be done with as little
as 3 additional fets, but probably more on the order or 7-10 for performance
reasons. So you're looking at programmable on chip integrators for around 10
mosfets a piece. Of course, you'd use a technology size larger than what is
used for digital logic because the analog toolchain would be more sensitive to
problems like channel noise, gate tunneling, etc. You would not want to use a
differentiator because they tend to amplify noise in an unstable and
uncontrollable fashion and are not required for functional completeness (the
analog equivalent of Turing completeness).

Edit: IQ analog processing is extremely common in the high performance RF
field but tends to be static and not reprogrammable. FPAA's exist on market
but are extremely expensive for what you get. The general purpose analog
computer was initially developed by Shannon (yes that Shannon) back in the
40s.

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dwarman
I see they re-invented asynchronous logic, such as Chuck Moore's chip today
uses, for their digital fabric.

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PeachPlum
My dad's analogue computer ran the payroll at Raleigh Bicycles.

They had an arrangement with Cadbury, who had the same machine, that if either
broke down at wages time, operators could drive the 60miles and run the batch
on the other's machine.

I find it interesting my family heritage is

Father - computer mechanic Grandfather - machine maintenance at John Player
Cigarettes Great-Grandfather - machine maintenance at a Nottingham Lace
factory

Me - computer programmer / analytics

~~~
zokier
Forgive my ignorance, but wouldn't payroll be particularly unsuitable domain
for analog computing? There is very little that can be considered continuous
in payroll, and on the other hand the exactness of values is very important?

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PeachPlum
meaning electro mechanical

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tonmoy
So the GGP is actually talking about a different kind of "analog" computer
compared to what the article is talking about?

