8-N-1 is a common shorthand notation for a serial port
Serial port
In computing, a serial port is a serial communication physical interface through which information transfers in or out one bit at a time...

 parameter setting or configuration
Computer configuration
In communications or computer systems, a configuration is an arrangement of functional units according to their nature, number, and chief characteristics. Often, configuration pertains to the choice of hardware, software, firmware, and documentation...

  in asynchronous
Asynchronous start-stop
Asynchronous serial communication describes an asynchronous, serial transmission protocol in which a start signal is sent prior to each byte, character or code word and a stop signal is sent after each code word...

 mode, in which there are eight (8) data bit
A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...

s, no (N) parity bit
Parity bit
A parity bit is a bit that is added to ensure that the number of bits with the value one in a set of bits is even or odd. Parity bits are used as the simplest form of error detecting code....

, and one (1) stop bit.

8-N-1 is the most common configuration for PC
Personal computer
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...

 serial communications today.

The abbreviation is usually given together with the line speed in bits per second, as in 9600/8-N-1. The speed includes bits for framing
Data frame
In computer networking and telecommunication, a frame is a digital data transmission unit or data packet that includes frame synchronization, i.e. a sequence of bits or symbols making it possible for the receiver to detect the beginning and end of the packet in the stream of symbols or bits...

 (stop bits, parity, etc.) and the effective data rate is lower than the bit transmission rate. For 8-N-1 encoding, only 80% of the bits are available for data (for every eight bits of data, ten bits are sent over the serial link — one start bit, the eight data bits, and the one stop bit). This mode was also commonplace for the link between modems until the 1990s when Link Access Procedure for Modems became widespread. 8-N-1 continued in use for the computer to modem connection.
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