Winn L. Rosch Hardware Bible, Sixth Edition

Parallel Ports

The defining characteristic of the parallel port design is implicit in its name. The port is “parallel” because it conducts its signals through eight separate wires—one for each bit of a byte of data—that are enclosed together in a single cable. The signal wires literally run in parallel from your computer to their destination—or at least they did. Better cables twist the physical wires together but keep their signals straight (and parallel).

In theory, having eight wires means you can move data eight times as fast through a parallel connection than through a single wire. All else being equal, simple math would make this statement true. Although a number of practical concerns make such extrapolations impossible, throughout its ...