Parallel cables are not included in the CompTIA A+ 220-1001 objectives, but I’ll mention it here for background. Parallel cable transmits multiple bits simultaneously. However, electrical signal interference from adjuste wires is often an issue, and therefore parallel cable had smaller transmission distances than serial cables.
Serial cables transmit data one bit a time, which turns out to be faster than parallel cables and is therefore more common than the older parallel cable types.
Serial cables include Universal Serial Bus (USB) and Serial ATA (SATA).
DB-9 serial connectors can be used on a router, switch, firewall, etc.
DB stands for D-subminiature or D-sub. There are many different sizes from A through E.
These connections send serial data over an RS-232 connection. RS-232 stands for Recommended Standard 232.
Serial communications standards were meant for modem communication, printers, mice, networking equipment.
