Introduction to Analog Computing

An (electronic) analog computer may be characterised as follows:

• An analog computer is based on the creation of a model which represents the problem to be solved.
• Although most (electronic) analog computers work with (quasi) continuous values (voltages in most cases), this is not a necessary condition for an analog computer. What makes an analog computer an analog computer is the fact that it resembles a model (an analog) for the problem to be solved with its help (in fact there were quite some digital implementations of analog computers, so called Digital Differential Analyzers, DDAs for short).
• Basic computing elements of an analog computer are summers, integrators, multipliers, function generators and comparators. Depending on the problem to be solved specialized computing elements like resolvers, time delay devices etc. were employed, too.
• Programming an analog computer consists of the transformation of the equations describing the problem to be solved into an analog (being a model) computer circuit. This circuit is then implemented using the aforementioned computing elements.

The following links point to introductory material covering the technology of analog computers, the art of programming these machines and their history.

• Dr. F. Vogel wrote a great introduction (in German) to analog computing with lots of worked examples.
• An Introduction to Analog and Hybrid Computing: This set of slides was prepared for an introductory talk at the VCFE 7.0 (2006) in Munich and give an overview of the basics of analog computing.
• Workshop - Analog Computing - slides covering the solution of three typical problems on an analog computer in detail. These examples are 1) mass-spring-damper system, 2) Lynx/Rabbit ecosystem and a 3) bouncing ball in a box. These slides (about 700 kB) were also prepared for a talk to be given at the VCFE 7.0 2006 in Munich.
• The following slides, Telefunken Analog and Hybrid Computers , give a short overview of Telefunken's developments in the area of analog and hybrid computing (about 4.5 MB). I created these slides for a talk to be given at the VCFE 7.0 2006 in Munich.
• My personal favourite link is the one to EAI's multimedia lecture Understanding the ANALOG/HYBRID Computer. This course gives a simple introduction to the principles of an analog computer with some examples. The original lecture consisted of eighty slides and a corresponding audio tape. Both have been merged into a podcast by my friend Christian Peters.
• Another interesting resource are the annotations for an ancient slide collection covering the TELEFUNKEN analog computers - Dia-Reihe Analogrechner, in German, 27 MB!
• A Practical Approach to Analog Computers by John D. Strong and George Hannauer gives a good introduction to analog computing using the then new EAI-231R tube based analog computer, one of the finest instruments ever made.
• A very comprehensive text is the quite famous Handbook of Analog Computation from EAI.
• Fundamentals of the Analog Computer by Dr. Howe, one of the original founders of ADI.
• Analog was not a Computer Trade Mark a wonderful introductory paper written by George Fox Lang, Data Physics Corporation, published in the August 2000 issue of "Sound and Vibration".
• Thanks to Mr. Knut Rothstein I am able to present the scans of the EAI-brochure Simulation by Hybrid Computer - the Unbeatable Competitive Edge which he generously donated to the collection.
• Joe Sousa maintains the Philbrick Archive - an incredibly valuable collection of materials about Philbrick's operational amplifiers etc. If you are looking for more information about the famous K2-W amplifier or the like this is the right place.
• Introduction to Electronic Analogue Computing by Lawrence T. Bryan, Louis C. Just and Gerard S. Pawlicki (English, ca. 0.5 MB)
• Handbook of Analog Computation - a great introduction into the art of analog computing (24 MB).

22-DEC-2009, ulmann@analogmuseum.org