Foundation Topics: Understanding I/O Ports

I/O ports are used to send information to and from the processor and memory. While the most important I/O port on recent systems is the USB port, you might also encounter other ports, including legacy ports such as serial and parallel. The following sections explain the major features of each port type covered by the A+ Certification exams.

USB

Universal Serial Bus (USB) ports have largely replaced PS/2 (mini-DIN) mouse and keyboard, serial (COM), and parallel (LPT) ports on recent systems. Most recent desktop systems have at least four USB ports, and many systems support as many as eight or more front- and rear-mounted USB ports. Figure 7-1 shows the rear panel of a typical ATX system, including USB and other port types discussed in this chapter.