The computer that guided Apollo astronauts to the Moon had a tiny fraction of the memory of a modern computer.

The Apollo Guidance Computer, built by MIT and used aboard both the command module and lunar module, ran at a clock speed of about 2.048 MHz and had roughly 4 kilobytes of erasable memory for active calculations, alongside about 72 kilobytes of fixed, read-only memory holding its programs.

Despite these modest specs by today’s standards, it was a genuine breakthrough for its time: one of the first computers to rely on integrated circuits, and reliable enough to handle real-time navigation and guidance, including recovering from a series of program alarms triggered by an overloaded task queue during the final minutes of the actual Apollo 11 landing.