Standard Serial and Parallel Ports
Traditionally, the most basic communications ports in any PC system have been the serial and parallel ports, and these ports continue to be important.
Serial ports (also known as communication or COM ports) originally were used for devices that had to communicate bidirectionally with the system. Such devices include modems, mice, scanners, digitizers, and any other devices that "talk to" and receive information from the PC. Newer parallel port standards now allow the parallel port to perform high-speed bidirectional communications.
Several companies manufacture communications programs that perform high-speed transfers between PC systems using serial or parallel ports. Versions of these file transfer programs have been included with DOS 6.0 and higher (Interlink) and with Windows 95 and newer versions (Direct Cable Connection [DCC]). Although USB continues to replace the parallel port in new computers, you can still purchase products that make nontraditional use of the parallel port. For example, external drive vendors continue to make CD-ROM, CD-RW, and DVD drives; floppy drives; print servers; and tape backups that connect to the parallel port, although many of these devices also include USB connections as well.
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