Parallel Interface
The parallel port was originally created for communication with a printer and thus is called a printer port. A PC may have at most 3 parallel ports, which are named LPT1, LPT2, and LPT3. A printer port female connector has 25 pins and is shown in Figure 2-4.
Figure 2-4. Parallel interface connector (female).
At least 8 wires are needed for parallel transfer of 8 bits, but the standard IBM-type printer port uses 17 wires for data transfer plus some more to ground the system. These extra wires are used in an intense hand-shaking process between a PC and a printer.
The computer puts 8 data bits on the 8 data lines and sends (on ...
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