The Charming Genius of the Apollo Guidance Computer
summary
The Apollo Guidance Computer runs at ~1 MHz with 15‑bit words (one parity + 15 data), about 248 words of RAM and ~36K words of ROM implemented as core rope memory, weighs ~70 lb and draws ~55 W. It implements a priority‑scheduled real‑time executive with a small waitlist and a 12‑slot core set, five interrupts and the DSKY interface. Rescue story: spurious radar uplink soaks ~80% CPU, triggers executive restarts yet priority scheduling keeps program 63 (descent) running and the landing succeeds; Margaret Hamilton’s Colossus software is the verified flight code.
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chapters (25)
- 0:00Start
- 0:15Prohibition against Swearing
- 2:06System Checks
- 2:45The Translunar Injection
- 3:15Free Return Orbit
- 4:30The Lunar Orbit Rendezvous
- 4:48The Apollo Spacecraft
- 5:53Lunar Module
- 6:21Orbital Paths
- 7:11Universal Coordinate System
- 7:50The Deep Space Network
- 9:14High Gain Antenna
- 9:47Celestial Navigation
- 10:33Star Charts
- 11:25Optics Assembly
- 11:50Dead Reckoning
- 12:29Inertial Guidance
- 14:19Gimbal Lock
- 20:09The Apollo Guidance Computer
- 25:08Digital Autopilot
- 28:06What Is the Executive
- 28:44System Restarts
- 30:10Priority Scheduling
- 32:20Capture Breaking
- 37:06Steadies the Thrust Vector
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