How can I hack & build upon (i.e. add DVD drive, USB reader, etc.) a BitCoin miner like (Butterfly Jalapeño).
Everyone tries to use their gaming computer as miner but I want to venture & try to get insane performance by using parts of a miner & build a PC from it.
Or it is impossible?
This is not possible.
ASIC mining devices like those sold by Butterfly contain hardware that is capable of computing SHA256 hashes at high speed, but nothing else. They are not general purpose CPUs and cannot be reprogrammed to run other code.
They might contain a simple microprocessor or microcontroller to control the ASICs and interface with the host computer, and in principle you could run other code on that, but it would have to be your own custom code as these chips are presumably not x86, and the performance is probably too low to play anything more complex than Pong. Moreover, these devices have no graphics hardware and no obvious way to connect it. It would be like trying to play Call of Duty on your microwave oven.
