7.1 SERIAL STANDARDS
Most serial ports obey some variant of the standard known as RS-232. This standard specifies the electrical characteristics and meaning of each signal wire, as well as pin assignments on the traditional 25-pin (DB-25) serial connector shown in Exhibit A.
Exhibit A A male DB-25 connector
Full RS-2321 is overkill for all real-world situations, as it defines numerous signals that are unnecessary for basic communication. DB-25 connectors are also inappropriately large for use on patch panels and laptop computers. As a result, a number of alternative connectors have come into widespread use. These are described in the section ...