16 lines
915 B
Plaintext
16 lines
915 B
Plaintext
bit bang
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n. Transmission of data on a serial line, when accomplished by rapidly
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tweaking a single output bit, in software, at the appropriate times. The
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technique is a simple loop with eight OUT and SHIFT instruction pairs for
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each byte. Input is more interesting. And full duplex (doing input and
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output at the same time) is one way to separate the real hackers from the
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wannabees. Bit bang was used on certain early models of Prime computers,
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presumably when UARTs were too expensive, and on archaic Z80 micros with a
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Zilog PIO but no SIO. In an interesting instance of the cycle of
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reincarnation , this technique returned to use in the early 1990s on some
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RISC architectures because it consumes such an infinitesimal part of the
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processor that it actually makes sense not to have a UART. Compare cycle of
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reincarnation. Nowadays it's used to describe I2C, a serial protocol for
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monitoring motherboard hardware.
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