The Ultimate Apollo Guidance Computer Talk

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Lorenzo von Matterhorn
Jan 31, 2009
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It's mind boggling that this revolutionary thing could reliably do everthing described from 45:42 onward using this hardware:

Apollo Guidance Computer (AGC) and DSKY
Invented by: Charles Stark Draper Laboratory
Manufacturer: Raytheon
Introduced: August 1966; 51 years ago
Discontinued: July 1975; 42 years ago
Processor: Discrete IC RTL based
Frequency: 2.048 MHz
Memory: 16-bit wordlength, 2048 words RAM (magnetic-core memory), 36,864 words ROM (core rope memory)
Ports: DSKY, IMU, Hand Controller, Rendezvous Radar (CM), Landing Radar (LM), Telemetry Receiver, Engine Command, Reaction Control System
Power consumption: 55 W
Weight: 70 lb (32 kg)
Dimensions: 24×12.5×6.5 inches (61×32×17 cm)

42 AGCs were built. The locations of most of the 21 which were not flown are not known.

First, AGC overview: 0 through 3:20. Next, detailed architecture and programming info. Next, flight events from launch: 45:42 to end.

There is a great book on the AGC that describes how it was built and gets a bit into how it works. "Journey to the Moon: The Story of the Apollo Guidance Computer", published by the AIAA. I particularly like the concept of "rope memory" :). You can buy it from the AIAA a bit cheaper than Amazon if you are interested I think.

IIRC at the time it was being made it consumed 60% of world IC production.

They commenced design in 1961 so by the time it flew it was quite obsolete (given the pace of computer development back then, particularly the acceleration of the new "Integrated Circuit" technology! Because of all the checking for flight qualification, the newly developed more powerful units were not able to be installed.

More discussion on it here: