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In data transmission, parallel communication is a method of conveying multiple binary digits simultaneously using multiple conductors. This contrasts with serial communication , which conveys only a single bit at a time; this distinction is one way of characterizing a communications link .
In telecommunication and data transmission, serial communication is the process of sending data one bit at a time, sequentially, over a communication channel or computer bus. This is in contrast to parallel communication , where several bits are sent as a whole, on a link with several parallel channels.
These blocks convert data between serial data and parallel interfaces in each direction. The term "SerDes" generically refers to interfaces used in various technologies and applications. The primary use of a SerDes is to provide data transmission over a single line or a differential pair in order to minimize the number of I/O pins and ...
(the START bit), waits 'half a bit duration' and then reads the value of the signal. A further delay of one 'whole bit duration' is executed before the next data bit is 'read' - repeating for the length of the whole serial word (typically 7/8-data bits). An optional PARITY bit follows the data bits and precedes the stop bit(s).
At the destination, a second UART re-assembles the bits into complete bytes. Each UART contains a shift register, which is the fundamental method of conversion between serial and parallel forms. Serial transmission of digital information (bits) through a single wire or other medium is less costly than parallel transmission through multiple wires.
While specific examples follow, countless other connectors have been used for RS-232 connections. The 9-pin DE-9 connector has been used by most IBM-compatible PCs since the Serial/Parallel Adapter option for the PC-AT, where the 9-pin connector allowed a serial and parallel port to fit on the same card. [4]
In general, parallel interfaces are quoted in B/s and serial in bit/s. The more commonly used is shown below in bold type. On devices like modems , bytes may be more than 8 bits long because they may be individually padded out with additional start and stop bits; the figures below will reflect this.
The last data bit is sometimes used as a parity bit. The number of data and formatting bits, the order of data bits, the presence or absence of a parity bit, the form of parity (even or odd) and the transmission speed must be pre-agreed by the communicating parties. The "stop bit" is actually a "stop period"; the stop period of the transmitter ...