About a month after Apollo 8 circled the moon my Dad and I traveled the two miles to Malmstrom Air Force Base for a tour of the SAGE installation. A number of these Semiautomatic Ground Environments were scattered around the country to detect and coordinate a response to bomber attacks from the Soviet Union. The cost was enormous - more than the Manhattan Project - with the effort resulting in several computing "firsts". It formed how I thought of computing at the time, blinding me to another more important revolution that was underway.
The SAGE building was enormous. It had to be to house the roughly supermarket sized FSQ-7 computer. These were tube based and designed to be redundant enough that statistically likely tube failures could be repaired by airmen with replacement modules that could be swapped inside of a minute. Outside the blast hardened building was a large cooling plant to keep everything from melting down.
The big show came with an airman pointing a light gun at a large circular display with radar blips from a number of radar stations. He'd pull the trigger and get some basic information on the airplane - friend or foe id, call sign, altitude, speed and heading. Should an intruder be spotted, interceptors would be scrambled. In Great Falls that meant F-106s from the Montana Air National Guard about seven miles to the West on Gore Hill. It was co-located with the commercial airport. I believe it was the only commercial airport in the US with nuclear weapons on site. All this was really impressive, but so was the fact that each of the radar terminals had an ash tray and a cigarette lighter.
I thought computers were huge expensive beasts - rare things that I might get to program some day, but certainly not anything that would be part of my life. It turned out what took place the month before provided a hint that didn't register until much later.
While many of the fundamental ideas behind computing had been put together in the fifties and sixties, miniaturization and the real start of Moore's Law really came with the space program. Simple integrated circuits had been developed, but size and weight requirements on the Apollo command module and the lunar lander called for huge advances. The advances were borderline unthinkable, but solved with cubic money and outstanding minds. My favorite example is the Apollo Guidance Computer. Books have been written and I wouldn't add anything, but here are a couple of gee-whiz links.
The first is from Ken Shirriff's terrific retro computing hardware blog. Ken's hobby is reverse engineering ancient electronics and restoring old computers. In this post he talks about core rope and the guidance computer. Programs were literally woven into a rope that was a simple core memory system. It's elegant in a hammer and tongs sort of way. If you don't know how core memory works go and check out the photographs and skip the technical parts of the text. It's a remarkable story involving women who could sew and sexism. And if you have the background it's even more interesting.
And here's a nifty Apollo Guidance Computer Simulator. Print out the instructions or open them in another window and play astronaut! Just in time for the 50th anniversary in a few weeks.
The dramatic infusion of R&D money built the semiconductor IC industry and established starter markets. There many other stories - like how AT&T and IBM worked together behind the scenes in the 60s and early 70s to bootstrap the necessary tool building. They did it for their own benefit, but without it we might be a decade behind where we are now. Perhaps a more interesting question might be: 'would that have been a good thing?' I've been thinking about that a lot recently.
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