rapidly changing a single output bit, in software, at the appropriate times. The technique is a simple loop with eight OUT and SHIFT instruction pairs for each byte. Input is more interesting. And full-duplex (doing input and output at the same time) is one way to separate the real hackers from the Bit bang was used on certain early models of Primecomputers, presumably when UARTs were too expensive, and on technique is now (1991) coming back into use on some RISCarchitectures because it consumes such an infinitesimal part of the processor that it actually makes sense not to have a
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