Users Guide

188 Glossary
POST
Acronym for power-on self-test. Before the operating system loads when you turn
on your system, the POST tests various system components such as RAM, the
disk drives, and the keyboard.
power supply
An electrical system that converts AC current from the wall outlet into the
DC currents required by the system circuitry. The power supply in a personal
computer typically generates multiple voltages.
power unit
A set of power supplies in a system chassis.
ppm
Abbreviation for pages per minute.
PPP
Abbreviation for Point-to-Point Protocol.
PQFP
Abbreviation for plastic quad flat pack, a type of microprocessor socket in which
the microprocessor chip is permanently mounted.
program diskette set
The set of diskettes from which you can perform a complete installation of an
operating system or application program. When you reconfigure a program, you
often need its program diskette set.
protected mode
An operating mode supported by 80286 or higher microprocessors, protected
mode allows operating systems to implement:
• A memory address space of 16 MB (80286 microprocessor) to 4 GB (Intel386 or
higher microprocessor)
• Multitasking
• Virtual memory, a method for increasing addressable memory by using the hard
drive
The Windows NT, OS/2
®
, and UNIX
®
32-bit operating systems run in protected
mode. MS-DOS cannot run in protected mode; however, some programs that you
can start from MS-DOS, such as the Windows operating system, are able to put
the system into protected mode.