1960s Computing - the Apollo Guidance Computer

[Slim]

I'm always interested in the technology of the Space Race but I found this particularly interesting as an examination of historic computing technology, especially from 10 minutes in when there's an interview with Albert Hopkins, who gives an introduction to the onboard computer used for the Apollo spacecraft.

Even in 1965 computers were said to be "dominating our lives" - at a time when a successful large business or university might own two or three of them. No-one had one on a desk at work, or at home, or in their pocket.

Mr Hopkins explains how the necessary technology had been miniaturised for the space programme. He shows the reporter some core rope storage roughly the size of a modern printer toner cartridge, and a logic gate roughly the size of a drawing pin.

These days both of these things are manufactured into tiny slivers of microchip. A modern microprocessor chip might contain a few hundred million logic gates, and a 16GB stick of RAM contains about 20,000 times the capacity of the storage unit shown in the film.

[pxr5]

Nice find. I've actually seen and used core rope memory like that. How things have changed. There's more power in my toothbrush than what they had then 

[Slim]

When I did my Comp Sci degree, core storage was still being taught. Just dug out my hardware text book The Principles of Computer Hardware, published in 1985. This was a compulsory first year text, mainly because it was written by our lecturer on the subject, Alan Clements.

He writes:

Ferrite-core memories belong to the adolescence of the computer industry... as semiconductor memory continues to plummet in price while offering higher densities (bits per chip), greater speeds and a much reduced power consumption, the ferrite core is fast becoming obsolete.

There are three reasons why the principles of ferrite-core memories are taught today. Firstly, they illustrate very well the two-state nature of digital devices. Secondly, and more cynically, their operations can readily be explained in a few pages and the question "Explain the principles of a ferrite core memory" helps to fill in a gap in all elementary computer science exams. Thirdly, the basic principles of ferrite-core memory may be extended to disk and tape units which still reign supreme in the province of backing storage.


.. then he goes into fantastic detail about magnetic field intensities, the magnetic effects of electron spin, thermal vibration between adjacent atoms and hysteresis curves, far more than we needed for the first year exams. I remember those exams very well, I spent some of the first year convinced I wouldn't get past them, mainly because of the maths and numerical methods modules and I was elated when I did. Thirty-seven years ago now, jeez