8-N-1 is a common shorthand notation for a serial port parameter setting or configuration in asynchronous mode, in which there is one start bit, eight (8) data bits, no (N) parity bit, and one (1) stop bit.^[1] As such, 8-N-1 is the most common configuration for PC 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 (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).

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