I implemented the SHA-256 hash algorithm and ran it on the Apollo Guidance Computer that we’re restoring, taking 10.3 seconds per hash. This isn’t my first experiment with absurd Bitcoin mining. I tried mining by hand with pencil and paper; this had a hash rate of 0.67 hashes per day. Using an IBM punch card mainframe computer from the early 1960s got the hash rate up to 80 seconds per hash. My fastest implementation was on a Xerox Alto (the famous 1973 computer that inspired the Macintosh), which performed 1.5 hashes per second. Thus, the Apollo Guidance Computer outperformed the older transistor-based IBM computer but not the Alto.
Ken does really good investigations and writeups, often on reverse-engineered retro-related things. And his blog has a tag cloud: here’s the Apollo section.
I saw him do it on the Alto on CuriousMarc’s channel.