What was the clock speed of the Apollo Guidance Computer?

The Apollo Guidance Computer had a clock speed of 2.048 MHz. This crystal-controlled timing reference powered the guidance computer used in both the Apollo command module and lunar module.

The figure can be confusing because the AGC divided that frequency internally. A two-phase process produced a 1.024 MHz clock for internal operations, while a further division generated a 512 kHz master frequency used to synchronize external spacecraft systems.

Despite its modest speed, the AGC was purpose-built for reliable real-time guidance, navigation, and control rather than general-purpose computing. It used discrete integrated circuits, core-rope read-only memory, and magnetic-core memory, with astronauts entering commands through the DSKY display-and-keyboard unit.

The AGC's 2.048 MHz reference should not be confused with its lower operating subdivisions or with modern processor speeds. Its significance came from dependable timing and carefully engineered software, which helped guide Apollo spacecraft through lunar orbit, landing, rendezvous, and return.