Before revision: Whether to use or not use parity Odd or even parity, if used The number of stop bits sent must be chosen (the number sent must be at least what the receiver needs) Mark and space symbols (current directions in early telegraphy, later voltage polarities in EIA RS-232 and so on, frequency shift polarities in frequency shift keying and so on) Asynchronous start-stop signalling was widely used for dial-up modem access to time-sharing computers and BBS systems.
After revision: Whether to use or not use parity Odd or even parity, if used The number of stop bits sent must be chosen (the number sent must be at least what the receiver needs) Mark and space symbols (current directions in early telegraphy, later voltage polarities in EIA RS-232 and so on, frequency-shift polarities in frequency-shift keying and so on) Asynchronous start-stop signalling was widely used for dial-up modem access to time-sharing computers and BBS systems.