bit bang

bit bang

Transmission of data on a serial line accomplished by 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 wannabees.

Bit bang was used on certain early models of Prime computers, presumably when UARTs were too expensive, and on archaic Zilog Z80 micros with a Zilog PIO but no SIO. In an interesting instance of the cycle of reincarnation, this technique is now (1991) coming back into use on some RISC architectures because it consumes such an infinitesimal part of the processor that it actually makes sense not to have a UART.
References in periodicals archive ?
It requires some skill to manoeuvre over the broken bit bang in the middle of the road as it's a narrow one with cars parked close of one anot-her on either side.
"I knew we were capable of this, and I knew we were capable of the times we ran, but we've been a bit banged up.
Stone said: "I was always confident as most of the time we were a bit banged up with injuries and I felt once we got those players back it would help us.
And Paula was a bit banged up but not seriously hurt when I swept her off her feet at Wildcat.
"Came in just a little bit banged up but still knew I needed to get out and get (a race) under my belt against this sort of field."
is a bit banged up and sore but otherwise thankfully okay.
"I know Warrington were down a little bit on troops and they are a bit banged up with the short turnaround.
He added: "A lot of what I am doing is maintenance work so after training I will always look a bit banged up because I have ice packs on everything, and I am resting everything.
"They're a bit banged up without Charles at the moment, but they're finding a way to win.
We're a bit banged up with injuries but some lads are coming back.