There's a nice hour-long video from the recent CCC which is all about the AGC. It's billed as the ultimate guide to the Apollo Guidance Computer, which has some pretty unusual instruction set features, like a store-with-skip-on-overflow-and-clear-it-too. The memory mapping is a delight too. Some memory locations act as do-something registers, and all registers also appear in the memory map, with interesting consequences.
"The Command Module and the Lunar Module each contained one AGC. First built in 1965 from 5600 integrated circuits, it was one of the first minicomputers, beating commercial machines like the PDP-8 in weight (32 kg) and power consumption (55 W). The Apollo program's size and weight limitations as well as the requirements for real-time guidance, navigation and control were pushing 1960s technologies to their limits. As a 15 bit one's complement big-endian accumulator machine with 36 kilo-words of ROM and 2 kilo-words of RAM, its design seems very foreign from today's perspective."
The talk, by Michael Steil and Christian Hessmann can be seen here:
https://www.youtube.com/watch?v=xx7Lfh5SKUQand there's a writeup on Hackaday
here.
The talk is in two parts: first the architecture, then the implementation. [Edit: nope, 5 parts...two software layers and then peripherals.]
Be sure to check
the other AGC thread too, for some of Jeff's thoughts.
