Your Phone Is Millions of Times More Powerful Than the Computer That Landed on the Moon
Answers: “how powerful was the apollo 11 computer?”
The computer that guided humans to the Moon in 1969 had:
- About 4 kilobytes of RAM. This article wouldn’t fit in it.
- 72 KB of permanent storage — less than a single photo from your phone
- A processor running at 0.043 MHz. A modern budget smartphone is roughly 100,000 times faster, and by more meaningful measures, millions of times more capable.
The Apollo Guidance Computer (AGC) was, by today’s standards, barely a calculator. It was also one of the most remarkable machines ever built — arguably the first computer anyone’s life ever depended on, in real time, a quarter million miles from help.
Its software was woven by hand. Programs were stored in “core rope memory”: copper wires threaded through or around tiny magnetic rings, one bit at a time, mostly by women recruited from textile factories. Engineers called it LOL memory — “Little Old Lady” memory. A single misthreaded wire could have doomed a mission.
And during the actual landing, the computer was pushed past its limits. Minutes before touchdown, the AGC flashed alarms — 1202, 1201 — codes even the astronauts didn’t recognize. A radar switch left in the wrong position was flooding it with junk data. The computer was overloaded… and it triaged: its scheduler dumped low-priority tasks and kept the landing calculations running. It crashed and recovered five times in four minutes without ever losing the ship.
A 26-year-old engineer, Jack Garman, recognized the alarm from a simulation and made the call: keep going. Neil Armstrong landed with about 25 seconds of fuel to spare.
The AGC’s legacy isn’t its specs. It proved that software — small, disciplined, ruthlessly prioritized — could be trusted with human lives. Every autopilot since is its descendant.