PBX (Private Branch exchange)
PBX and PABX (Private Automatic Branch eXchange) PBX is a telephone line can add an internal telephone network switching system, which is commonly known as a computer switchboard, PBX functions have the following number: external dial-up, ext exchange, telephone conference, telephone broadcast, voice mail and so on.
A new generation of PBX switching using digital means, exchangeable digital (digital) signals, but also interchangeable analog (analog) signals. General home phone telephone line to use two cores, while the commercial use of PBX phones use four-or six-pin cable.

PC Personal Computer
Personal computers for personal use of the computer, the origin of the name is because the high cost of early computers, only the enterprises can afford to purchase the use of personal computers is difficult to afford the cost of ownership, until beginning to low-cost computers for personal use before we can change this situation . So, broadly speaking, PC is a low priced computers, including APPLE produced by computer. In the narrow sense, PC refers to the IBM PC-compatible with the types of planes.

PC-DOS OS
Issued by the DOS version of the IBM name.

PCB Printed Circuit Board
Printed circuit boards for electronic components placement, there are line-based version. Manufactured using printing edition will be printed on the base copper corrosion lines and flush out the lines to be etched.