Bitcoin Mining On an Apollo Guidance Computer: 10.3 Seconds Per Hash

Slashdot reader volvox_voxel shares an excerpt from the latest blog post from software engineer Ken Shirriff, who is well known for his work on restoring some of the rarest computing hardware to its working condition: We’ve been restoring an Apollo Guidance Computer1. Now that we have the world’s only working AGC, I decided to write some code for it. Trying to mine Bitcoin on this 1960s computer seemed both pointless and anachronistic, so I had to give it a shot. Implementing the Bitcoin hash algorithm in assembly code on this 15-bit computer was challenging, but I got it to work. Unfortunately, the computer is so slow that it would take about a billion times the age of the universe to successfully mine a Bitcoin block. He wasn’t kidding about how long it would take to successfully mine a Bitcoin block. “The Apollo Guidance Computer took 5.15 seconds for one SHA-256 hash,” writes Shirriff. “Since Bitcoin uses a double-hash, this results in a hash rate of 10.3 seconds per Bitcoin hash. Currently, the Bitcoin network is performing about 65 EH/s (65 quintillion hashes per second). At this difficulty, it would take the AGC 4×10^23 seconds on average to find a block. Since the universe is only 4.3×10^17 seconds old, it would take the AGC about a billion times the age of the universe to successfully mine a block.”