I've always wanted more details about the orbital rendez-vous and coupling of the lunar lander with the orbiting command module. It happened without earth radar assistance and with high uncertainty in orientation, acceleration and mass. Or am I mistaken in this? Wasn't there also a gimbal lock problem? What was the Appolo Guidance computer actually doing? With what input? (Years later, the coupling of the shuttle with the ISS was heralded as a triumph in technique and astronaut's skill.) Wouter (conspiracy theories are lunatic, I'm just wondering how they pulled it off) -----Original Message----- From: Henry Baker Sent: Monday, July 15, 2019 11:02 PM To: math-fun@mailman.xmission.com Subject: [math-fun] Apollo Guidance Computer: 10 secs/SHA256 hash FYI -- 50 years of Moore's Law at (proof of) work: Mining Bitcoins on the Apollo Guidance Computer (see below). --- I've recently been learning about the detailed calculations of satellite GPS computations, so I'm much more interested in how quickly the AGC could do today's GPS calculations. BTW, Einstein's special relativity (satellite speed adjustment to the clock) and Einstein's general relativity (satellite altitude from the Earth's center) are both important: higher altitude clocks tick faster by ~45usecs/day, while fast orbiting satellites tick slower by ~7usecs/day, resulting in a ~38usec/day (11.4km/day=7.1miles/day) difference. Q: Did the Apollo Guidance Computer have to deal with corrections for relativity? --- http://www.righto.com/2019/07/bitcoin-mining-on-apollo-guidance.html Ken Shirriff's blog Bitcoin mining on an Apollo Guidance Computer: 10.3 seconds per hash We've been restoring an Apollo Guidance Computer. Now that we have the world's only working AGC, I decided to write some code for it. Trying to mine Bitcoin on this 1960s computer seemed both pointless and anachronistic, so I had to give it a shot. Implementing the Bitcoin hash algorithm in assembly code on this 15-bit computer was challenging, but I got it to work. Unfortunately, the computer is so slow that it would take about a million times the age of the universe to successfully mine a Bitcoin block. ... https://arstechnica.com/tech-policy/2019/07/computer-from-nasas-apollo-progr... Computer from NASA's Apollo program reprogrammed to mine bitcoin It takes the Apollo Guidance Computer 10 seconds to compute a single hash value. Timothy B. Lee - Jul 9, 2019 10:15 pm UTC _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun