[gbg] is passionate about the 6502 processor and he is also interested in bitcoins. A friend challenged him on the possiblity of mining bitcoins with an 8-bit Nintendo Entertainment System. [gbg] responded to the challenge by creating a neat hack. He made the Retrominer. Although it is no match for a dedicated ASIC, he spent a few nights transforming a 1985 NES into a bitcoin miner.
A bitcoin miner performs a SHA256 hash on a random value from the bitcoin network, relaying the result of that calculation back to the Internet. To relay the solution to the proof-of-work, the setup would require a bridge between the NES and the Internet. A Raspberry Pi was used for this task. A USB CopyNES created a way to get data into the NES. After doing some 32-bit math, the NES relays this into the bitcoin network through the Raspberry Pi.
Bitcoin mining has evolved from the use of CPUs to ASIC-mining. An ASIC (application-specific integrated circuit) is a microchip designed and produced for the specific purpose of mining bitcoins. ASIC-miners are very fast and efficient with some promising a speed of 1500 Gigahashes per second. Finding cryptographic solutions through CPU time has therefore become a financially unwise option.