It's just for fun, I believe it will be very slow
Anyone designed a asynchronous circuit (without clocking) which could calculate hash for fixed length input.
just for fun, the speed won't be high.
the bitcoin block header is 81 byte fixed length, so ....... a asynchronous circuit will be possible
and only 4 byte (32 bit) are input line, others could be a register which stores information other than nonce, and only updates after 4294967296 hashes.