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CUSTOMIZED INTEGRATED CIRCUITS (IC'S) FOR RS-232The basic functions of the RS-232 interface have been built into a set of integrated circuits. The two fundamental components of the IC implementation are the UART (pronounced ‘YOU-ART’) and the line driver. A simple RS-232 circuit that only implements asynchronous RS-232 requires a much more simplistic UART than a circuit that implements a synchronous interface. By sending programming commands to the UART, the CPU can configure the baud rate, start and stop bits, and operation of the handshake lines. The line drivers supply the actual voltage to the cable lines. A circuit designed to connect a computer to a PDA for backup and restore can safely assume a cable length of, say, less than six feet. The line driver for this circuit needs to be much less powerful than one designed to drive a 50 foot long cable in a high-noise environment. |
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