The Analog Thing FAQ - TheAnalogThing

This page contains a list of frequently asked questions (FAQ) about The Analog Thing (in short THAT). It's a great entry place to learn about THAT.

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What is analog computing?

Analog computing is an alternative to digital computing; ideally suited for dynamic systems modeling; ideally suited for neuromorphic AI applications; much more energy-efficient than digital computing; inherently safer than digital computing in the face of cyber threats; a great, hands-on way to learn about maths, engineering and systems; and simply an eye-opening experience.

What is THE ANALOG THING?

THE ANALOG THING is a high-quality, low-cost, open-source, and not-for-profit cutting-edge analog computer. You can think of it as a kind of Raspberry Pi that computes with continuous voltages rather than with zeroes and ones.

What is "THAT"?

THAT is an abbreviation of THE ANALOG THING.

Who is the team behind THAT and what is their motivation?

THAT is developed and distributed by the German tech start-up company anabrid under the brand name Analog Paradigm. Anabrid is planning to develop an analog computer on-a-chip to diversify today's digital computing monoculture with analog-digital hybrid computing. To support this initiative, anabrid uses its Analog Paradigm brand to promote the often much more efficient and safer analog computing paradigm. THAT is Analog Paradigm's response to the need for education and community activity around analog computing. In contrast to the Analog Paradigm Model 1 analog computer, THAT is small, highly affordable, open-source, and not-for-profit. It is analog computing for the future, for all. Analog Paradigm welcomes community contributions to THAT hardware, accessories and documentation.

What can I do with THAT?

THAT is typically used to model dynamic systems, i.e., systems that change in time according to some causal relationships. Examples include including market economies, the spread of diseases, population dynamics, chemical reactions, mechanical systems, the firing of neurons, a variety of mathematical attractors, and much more. Technically, THAT solves (sets of) differential equations by way of integration, and it produces results in the form of graphs representing relationships between dependent and independent variables. If you are not familiar with differential equations, then THAT is an excellent tool to familiarize yourself with them. You can use THAT for a variety of purposes: You can use it to predict in the natural sciences, to control in engineering, to explain in educational settings, to imitate in gaming, or you can use it for the pure joy of it. THAT can help you understand what is (models of), and it can help you bring about what should be (models for). More fundamentally, THAT allows you to explore a non-digital computational paradigm hands-on!

What do I need to work with THAT?

You need a set of plug cables, which is included with THAT. You also need a USB power supply with a USB-C plug. Since most people have spare USB power supplies, we decided not to include one with THAT and save the extra cost. You will also need something to read the output of THAT (voltages that change over time), such as a hardware or software oscilloscope. Software oscilloscopes are software programs that can run on digital desktop or laptop computers and typically read changing voltages through the sound card's audio input interface. Software oscilloscopes (including free and open source ones) are available for all major operating systems.

How does a Hello World program look like on THAT?

A good first program for "analog beginners" is the modeling of a damped oscillation in an isolated system. For a detailed explanation see: Damped oscillation

Is THAT a general purpose computer?

Yes and no. The term general-purpose computer is commonly used to describe digital stored-program computers that can execute arbitrary algorithms. While THAT does not belong in this category, it is a general-purpose analog computer in that it can solve any (set of) differential equation(s) within the means of its computing elements. By connecting multiple THATs in minion chains, it is possible to implement arbitrarily large analog computer patches involving any number of computing elements.

How can I program THAT?

Programming analog computers is about modeling change in time. Typically, this process starts by translating change in some dynamic systems into one or more differential equations. These equations are then translated into patterns of wire connections between the analog computing elements on THAT's patch field. These patterns of wire connections are analog computer programs. When a program is run, THAT solves the programmed differential equations and outputs their solutions as time-varying voltages.

If THAT is powered by USB, i.e., by 5 V-, then how is it possible that its machine unit is physically ±10 V?

THAT uses a TBA 2- DC/DC converter, which turns a 4.5 V- to 5.5 V- input into a ±12 V output.

Want more information on Digital-Analog Hybrid Systems? Feel free to contact us.

How can I obtain output from THAT?

THAT outputs the solutions of differential equations as time-varying voltages. In control applications, these can be used to drive actuators such as motors or valves. In lab or classroom settings, they are often visualized as graphs using oscilloscopes or plotters. In hybrid computing (where analog and digital computers work in tandem), analog-to-digital converters and digital-to-analog converters turn time-varying voltages into digital data and vice versa. The simplest way to read the output of your THAT is to connect it to the sound card of a digital computer which can then be used to visualize the output using digital oscilloscope software and to record, analyze, or otherwise process it.

Why do the plugs not go all the way into the patch panel?

This is one of several unconventional but intentional design moves that make THAT possible and affordable. The 2 mm plug cables were originally designed to plug entirely into a corresponding type of gold-plated socket. One of these sockets plus mounting costs about USD 1.00, which would add up significantly for the 186 plug positions on THAT's patch panel. We saved this cost by using an extra-thick top PCB with appropriately-sized, gold-plated through-holes. Since the length of the plugs is greater than the thickness of the PCB, we placed stop-limits below each plug hole to ensure that the small, contact-assuring springs halfway along the length of each plug make reliable contact. The result looks a little unexpected, but it works well and cuts the cost of the overall device by more than half.

With outputs varying between -10V to 10V, how can I use THAT to model quantities smaller or greater than that?

Translating patterns of change in dynamic systems into mathematical representations and further into analog computer programs commonly involves the scaling of quantities. Quantities are represented on analog computers in a voltage or current interval with fixed boundaries called the Machine Unit. On THAT, this interval is -10 V to +10 V. For the sake of simplicity, the Machine Unit is generally thought of as ± 1, regardless of the actual voltage or current interval of a given analog computer. To model arbitrary quantities on THAT, they can be scaled to make efficient use of the Machine Unit. Output can then be converted back to the original scale.

How can I use THAT to create useful models of very fast or very slow phenomena?

Translating patterns of change in dynamic systems into mathematical representations and further into analog computer programs commonly involves the scaling of speed. THAT allows compressing or stretching the independent variable time by several orders of magnitude. In this way, the instantaneous decay of a volatile compound can be simulated slowly enough for observation and interactive manipulation, while population dynamics occurring over decades or centuries can be simulated in the blink of an eye.

What computing elements are available on THAT?

THAT is designed to allow a wide range of interesting applications with a minimal set of analog computing elements. It offers five integrators, four summers, four inverters, two multipliers, and eight coefficient potentiometers. In addition, it offers two comparators, two precision resistor networks as well as capacitors, diodes, and Zener diodes. Where more computing elements are needed for a particular application, multiple THATs can be connected in minion chains.

How precise is THAT compared to a digital computer?

THAT is precise to about three positions after the decimal point, relative to its Machine Unit (±1). Comparing the precision of analog and digital computers is a bit like comparing apples and oranges. Analog computers usually handle quantities based on measuring only (“What is your body height?”). Digital computers, however, also handle quantities based on counting (“How many siblings do you have?”), which requires strict numeral precision. Consider this: A bank clerk getting the third decimal place of an interest rate wrong commits a severe error, while a tailor being off by a few micrometers when taking a client’s measurements has no such problem. Furthermore, numerical digital computing involves rounding, hence rounding errors, which can add up quickly in iterative loops. Analog computers do not operate numerically and do not round. In this sense, the great precision of today’s digital computers helps minimize a problem that is specific primarily to digital computing. In short, representing quantities as continuous voltages, THAT does not suffer from many issues inherent to binary value representations. While analog computer solutions can be affected by noise and instabilities, the precision of THAT is perfectly appropriate for most analog computer applications.

What is a minion chain?

THAT is designed to allow an extensive range of applications with a small set of computing elements. When applications require additional computing elements, it is possible to link multiple THATs in a "minion chain" using their "MASTER OUT" and "MINION IN" ports. Connecting the MINION IN port of a THAT to the MASTER OUT port of another THAT with a ribbon cable makes the first THAT the "master" and the second THAT its "minion" so they can work together and share the computing elements of both devices in the same program. There is no limit to the number of THATs that can be linked in a minion chain.

2+2 ≠ 4?

If you wonder why THAT computes something like 2+2 = -4, then you need to familiarize yourself with how the Components of The Analog Thing work. Summers on analog computers are typically negating. This means they yield the negative of the sum. This is a convention and needs some getting-used-to. If you like, you can simply feed the summer's output into an Inverter to obtain the "correct" sign.

Are THAT's inputs compatible with (possibly overloaded) outputs from other analog computers with +-15V supply voltage?

THAT's inputs are protected by supressor diodes which begin to conduct at about +-20V. It's no problem to connect an output from a +-15V circuit to THAT's inputs. But some inputs will be overloaded if the voltage exceeds about +-11.5V, because THAT's supply voltage is +-12V.

Is there a template to draw and share THAT patches?

Yes. You can download it from the THAT online documentation at https://the-analog-thing.org/wiki/File:THAT_wiring_sketch_tempate.pdf

Where can I view past issues of the newsletter?

https://the-analog-thing.org/#newsletter

If you are looking for more details, kindly visit Digital Signal Processing Products.

Where can I buy one?

OK all you Digital computer buffs here are some Survey questions I am posing on analog computers

This AKAT-1, by the way, is my favorite analog computer, as the look is soooooo cool. Wish I could own one.

Q1. If you could locate an analog computer in your budget range
a. would you buy it ?
b. If one you really liked came up, BUT outside your budget, how much would you consider paying for one in US$ or Euros ?

Q2a. If you were given or left a working analog computer, would you

A. keep it or
B. sell it, or
C. give it away ?

Q2b. If you were given or left a NON working analog computer, would you

A. keep it and work to get it fully operational or
B. sell it in a non working state, or
C. give it away, again in a non working state ?

Q3. Ok so lets for a now assume, you suddenly had a working analog computer come into your possession,

what task would you think you could do with it ?

Please DONT Google for an answer about the tasks one can do with such a machine, just answer from your existing knowledge base, as it interesting to me

Q4. If you had the chance to build a brand new state of the art Analog Computer, would you

A. jump at the chance
or
B. go nar, I would prefer to wait to get a vintage machine ?

Q5 Have you ever or do you currently owned an analog computer

A. Yes

B. No

Ok Q6. so early analog computer were made using various technologies.

A. all Mechanical ie Gears and Differentials or Rotatable Cardboard Disks


B. all Vacuum Tube Valves



C. Transistors era


D. early integrated circuits.
next 2 pics are from this wonderful web site
http://www.earlycomputers.com/cgi-bin/item-report-main.cgi?a


So out of A,B,C and D styles

the question 6 is from the 4 constructional types just mentioned, do you have a preference of type you would like to own ?


Q7 Do you own any paper books on Analog computers ? and if so how many ?

and the last question for now is

Q8 Do you have any parts of or from an Analog computer ?

if so A. are you looking to find more of that machine ? maybe to get it working.
or B are you maybe thinking of selling or disposing of these parts

Looking forward to hearing answers

thanks in advance for reading and hopefully answering

As a parting note this is a pic of my EAI TR-20 Analog computer. Its such a great machine and I am so proud to have it
Whilst analog computers can still solve differential equations there is one major problem with using them in the modern world. That is the accuracy of the solution cannot be measured. On the other hand you can generate approximations to the solutions to a much greater range of differential equations to any required accuracy.

If you want to try this for yourselves GNU Octave is a free "MatLab like" program which will do this...

https://www.gnu.org/software/octave/

Note that unlike an analog computer which actually integrates, digital tools only generate an approximation of the integral. You can control how accurate it is, and make the error as small as you want, but there will always be some uncertainty in the answer. The smaller you make it the more calculations you will need to be performed, and so the time to produce a solution will extend. One popular tool which solves differential equations numerically is the SPICE circuit modelling tool. It has settings which allow the acceptable error to be controlled.

If any one wants to play with Analog Computers but does not have one, there are some components for LTSpice which allow one to be simulated..

http://www.edn.com/design/analog//A-virtual-analog-computer-for-your-desktop

of course this is really using digital approximations under the covers so it isn't real.

Analog Computers continued in use for long after digital computers could solve these problems. This was for a couple of reasons, firstly they were much cheaper than digital computers so could be widely deployed. Secondly, and IMHO most importantly, is that when the differential equations are with respect to time, which many are then an analogue computer solves these at a constant rate proportional to that time.

So for example in an Aircraft Simulator where many differential equations may need to be solved, analog computers can easily be used, because the inherently work in real time. Doing the same task with digital computers is harder because you have to sync the solution to real time, which can be harder than actually solving the equations....

Whilst analog computers can still solve differential equations there is one major problem with using them in the modern world. That is the accuracy of the solution cannot be measured. On the other hand you can generate approximations to the solutions to a much greater range of differential equations to any required accuracy.

Hi Dave, thanks for that full and informative reply. At this moment One point I like to make, I think this paragraph is missing the words "with Digital computers" to make it completely non ambiguous.

This I feel what you are saying is
"Whilst analog computers can still solve differential equations there is one major problem with using them in the modern world. That is the accuracy of the solution cannot be measured. On the other hand with DIGITAL computers you can generate approximations to the solutions to a much greater range of differential equations to any required accuracy."

This I feel is what you are saying. Hope this is what you meant ?

regards
David Q1..2: Probably I would buy it, keep it and if something is damaged, try to get as many blocks into operation as possible.

Q3: What is it for... solving equations of course, it may be a bit hard to get OS on it . This AKAT-1 you shown, built by Mr Karpiński, is loosely based on early ARR - Differential equations analyzer made in .

Q4: Depends on state of my trash bin in my basement. If there are lots of spare parts, I would try to build something.

Q5: A slide rule only.

Q6: Because of space requirements, the only analog computer that will fit in my cave would be transistor-based. Or hybrid circuits/ICs. Maybe some small one, see this Soviet small educational unit with switchboard, generators, filters, integrators and a small scope.

Q7: I have lots of books about analog computers, some date from early s. Most in Polish. Well, from this knowledge I could build one.
BTW but the strangest book in my collection is still one about building binary logic circuits using... hydraulics.

Q8: Probably not.

Is this electronic based analogue computing, or is mechanical based included as well?

There are lots of 50s era mechanical computers around, thing the Mk4/4A ground position indicators from the Canberra or Vulcan. There are also a Mk6 but only seen one. The bombsight computers from WW2 are available. I have a dead reckoning table that recorded the track of a ship that needs rebuilding.

Has anyone been to HMS Belfast and seen if that still has the analogue fire control computers? Really would like to go and see, but that is London.

These are of course specialised computers but wheter thay can be sensibly adapted for other uses I don't really know.

Hi there,

yes this post is about all mechanism types of analog computer. In fact in my initial (a) part Q6 I had a photo of a mechanical gun computer,
So yes this post is for discussion on all types,

I have not been to see HMS Belfast, maybe in September on my way back from Europe as I head home to Aus, I will try an go look.

Would you be able to post some pics of that dead reckoning table you have here please ?

Q1..2: Probably I would buy it, keep it and if something is damaged, try to get as many blocks into operation as possible.

Q3: What is it for... solving equations of course, it may be a bit hard to get OS on it . This AKAT-1 you shown, built by Mr Karpiński, is loosely based on early ARR - Differential equations analyzer made in .

Q4: Depends on state of my trash bin in my basement. If there are lots of spare parts, I would try to build something.

Q5: A slide rule only.

Q6: Because of space requirements, the only analog computer that will fit in my cave would be transistor-based. Or hybrid circuits/ICs. Maybe some small one, see this Soviet small educational unit with switchboard, generators, filters, integrators and a small scope.

Q7: I have lots of books about analog computers, some date from early s. Most in Polish. Well, from this knowledge I could build one.
BTW but the strangest book in my collection is still one about building binary logic circuits using... hydraulics.

Q8: Probably not.

Thank you MCbx for your detailed answer. I was interesting to see your responses to each question, especially a couple of them/

I think a lot of computer foke forget that a slide rule is actually a form of analog computer.

Your reply to Q6 was very very interesting, I clicked on that Soviet link.. Its an AMAZING machine. Thank you for that link.. I RECOMMEND all reading this post do have a look at it.

http://www.leningrad.su/museum/show_big.php?n=

I also like the comment on the odd book of building binary logic circuits using... hydraulics.

I saw where a MIT Grad made part of a computer logic gate using water
http://www.blikstein.com/paulo/projects/project_water.html

Have not read the whole article.

maybe you should look at trying to find remains of one in your 'neck of the world' When you get to analog mechanical systems, the question inevitably arises "What's a computer?"

If you say "that which computes an output from more than one input", then we've been surrounded by computers for at least 100 years or more. Consider the ordinary water meter. It takes a flow over time and integrates it to show consumption. Is it a computer?

When I was still going to school in the dark ages, I spent my summers working as an instrumentation tech in a steel mill. While there were certainly electronic systems, there were also pneumatics and hydraulics as well. You could start with a differential pressure across a venturi and perform calculations to show flow and consumption all using pneumatics. There were adders, subtractors, multipliers and even square-root extractors--all pneumatic/mechanical. No wires--just lots of 1/4" copper tubing carrying signals (IIRC) from 3-15 psi.

Nobody, to the best of my knowledge, called them "computers".

So were they?