Analog Computers

My interest in computers first arose because my ever-generous parents used what little spare money they had to buy me an electronics kit at the age of 10 or so. I remember to this day some 45 years later the excitement of that purchase. The kit had 4 transistors (OC70/OC71 and I think an OC170 RF transistor), and using that and a large number of resistors and capacitors, aerials and switches on a spring-loaded board one could build a huge assortment of projects. None of them were computers, but the desire to make things was stimulated. That was about 1962.

It sparked an interest in electronics that has never faded, even though the kit itself has unfortunately departed through the years.

In my early years at high school at the newly-built Queen Charlotte College near Picton, New Zealand - the first purpose-built form 1-6 college in New Zealand - I and others in my class were very fortunate to have what was probably the highest quality selection of public-school teachers in New Zealand. Queen Charlotte College was an experiment and a draw card for teachers who thought outside the box. (in New Zealand the public schools are government-funded, while private schools are paid for by parents).

Three of us in our mathematics class, myself, John Peek (now Hammond Peek and an Oscar-winner) and one other whose name embarrassingly slips my memory (David Whyte?) were encouraged by our teacher, Malcolm Gray, to construct a very basic binary adding machine. This was around 1966 and computers of any form were very unusal. The adding machine comprised two rows of multi-pole switches that could be set to 0 or 1, while a set of small torch bulbs run by a battery showed the current ‘add’ state of each column, with carry from the previous column. Crude, but fascinating at the time. We made the local paper and were probably the first true ‘nerds’ in the college, although that term came into being somewhat later.

At the time digital computers were not the only computers used, unlike now. Analog computers used varying voltages, resistor networks and operational amplifiers to simulate real-life situations. They were specialist devices, but extremely powerful given the right tasks. While I built a number of the components of an analog computer, I have never had the opportunity to see or use a real one. Unfortunately, the chance of ever finding an analog computer at a price point I could afford is vanishingly small, so when two brochures came up on our local auction site a while back, I couldn’t resist the opportunity to have them to share.

The first is from the company EAI for their PACE range and is a brochure for the TR-20 and TR-48 Analog Computers, the second is from the same company but is a Products & Services Catalog. Neither is dated but the catalog has a Business Reply Card attached with the date Nov 20 1964 stamped on it, so I think that can be assumed to date them fairly accurately. Deep inside the Catalog is a copyright 1964 notice. I’ll list the models in the catalog later so the search engines pick them up. It’s too hard at this stage to use OCR to get the text.

Use the links to the left to read each item.