A 35 kg block with ferrite ring storage – nevertheless, the hobbyist Ken Shirriff has been able to configure the restored Nasa AGC to mine Bitcoin. That cost a lot of effort and manual adjustment of the Sha-256 algorithm, said the developer.

Computer historians got an Apollo Guidance Computer from NASA from the 60s up and running. On the collector’s item from a private range, the developer Ken Shirriff has also tried to operate on the system Bitcoin mining. The result: The AGC can calculate a Sha-256 hash value in ten seconds, writes the IT magazine Ars Technica. “The computer is so slow that it would take about a billion times the life of the universe to successfully dig a bitcoin block,” says Shirriff.

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In addition to this extremely slow computing power, the hobbyist had problems with getting the Bitcoin algorithm to work at all. The AGC processes instructions in 15-bit format. Modern computers and mining asics use 32 or 64 bits. This is also true for Sha-256’s 32-bit operations used in bitcoin mining. That’s why he split the algorithm into three parts: a 4-bit part and two 14-bit parts, which the computer processes one at a time.

4 kbyte memory for Sha-256

Shirriff also had to write some memory instructions in subroutines themselves that use modern computers and also Sha-256 – such as Rotate and Shift. The memory itself is a problem that is about 4 Kbytes in size and stores information in magnetized ferrite rings. “I managed to squeeze everything into a memory bank using the same 16 words for multiple purposes,” says Shirriff. That had been associated with much debugging.

The AGC was used by NASA for many Apollo missions as a navigation computer. He was modern for the time, as he was already equipped with integrated circuits and weighed only about 35 kg. In 2016 hobbyists could save a copy from scrapping and get it working again.

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