DB (D-Sub) Connectors and COM Ports
If present, the serial port on the back of a PC is a male 9-pin connector (DE-9 D-sub connector). Earlier PCs may have had two 9-pin connectors or one 9-pin and one 25-pin (DB-25). On a PC, serial ports are called "COM ports," identified as COM1, COM2, etc. See COM1 and D-sub connectors.
Serial, Parallel and Game
In earlier PCs, one or two serial ports, one parallel port and one game port were included on the motherboard. On the first PCs, these ports were contained on a stand-alone expansion board plugged into the ISA bus. Contrast with parallel port. See serial interface and RS-232.
Faster, But Still Serial
The USB and FireWire (IEEE 1394) interfaces were added to PCs in 1998, offering a quantum jump in transfer rate, plus the ability to daisy chain large numbers of devices on the same bus. Like the legacy serial port, USB and FireWire are also serial interfaces. See USB and FireWire.
![]() | Reproduced with permission from Computer Desktop Encyclopedia. Copyright (c) 1981-2008 The Computer Language Company Inc. All rights reserved. |
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