Apollo Guidance Computer’s Bitcoin Mining Demo Shows Vast Gap to Modern Network

Computer scientist Ken Shirriff demonstrated that an Apollo Guidance Computer (AGC)—the 1970s navigation computer that guided lunar missions—can run Bitcoin’s proof‑of‑work algorithm. The experiment, first posted in 2019, resurfaced in crypto media this week as a vivid illustration of how far Bitcoin mining has progressed.

How the AGC Performs Bitcoin Mining

The AGC weighs about 70 lb, contains roughly 4 KB of RAM and 36 KB of ROM, and can execute around 40,000 additions per second. Shirriff wrote mining code in AGC assembly language. The computer required 5.15 seconds to compute a single SHA‑256 hash; because Bitcoin hashes each block header twice, the effective rate was one hash every 10.3 seconds.

Historical Network Difficulty vs. Today

When Shirriff performed the test, the Bitcoin network’s hashrate was about 65 exahashes per second (EH/s). At that difficulty, the AGC would need roughly 4 × 10²³ seconds—about one million times the age of the universe—to discover a block.

As of September 2026, the network’s hashrate has risen to 934 EH/s, roughly 14 times the 2019 level. Scaling the original estimate, the AGC would now require about 5.8 × 10²⁴ seconds, or roughly 13 million times the age of the universe, to find a block.

Context and Relevance

The demonstration underscores the massive computational power required for Bitcoin’s proof‑of‑work system. Even a historic computer that once guided astronauts to the Moon is orders of magnitude slower than today’s specialized mining hardware.

Bitcoin’s price recently reached $81,000, and mining difficulty remains high, with block subsidies still providing the bulk of miner revenue.