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Bitcoin Mining on a 55 year old 1401 mainframe

An old IBM mainframe was setup with the SHA 256 hashing algorithm. It took around 80 seconds to complete one hash. To put that in perspective most ASICs hit around a trillion or more hashes per second.

Could an IBM mainframe from the 1960s mine Bitcoin? The idea seemed crazy, so I decided to find out. I implemented the Bitcoin hash algorithm in assembly code for the IBM 1401 and tested it on a working vintage mainframe. It turns out that this computer could mine, but so slowly it would take more than the lifetime of the universe to successfully mine a block. While modern hardware can compute billions of hashes per second, the 1401 takes 80 seconds to compute a single hash. This illustrates the improvement of computer performance in the past decades, most famously described by Moore's Law.