RadiSys EPC-5A, Справочное руководство по аппаратному и программному обеспечению

Страница: 146 / 156

EPC-5A Hardware Reference
G-8
Memory: A designated system area to which data can be stored and from which data
can be retrieved. A typical computer system has more than one memory area.
See Conventional Memory and Extended Memory.

O

Offset: The difference in location of memory-mapped data between the physical
address and the logical address.
Operating System: See Disk Operating System.

P - Q

PCI Mezzanine Card (PMC): A new standard form factor for PCI add-in modules.
PMCs mate with their respective connectors on the motherboard and are
secured with screws.
Peripheral Connect Interface (PCI): A popular microcomputer bus architecture
standard.
Peripheral Device: An external device connected to the system for the purpose of
transferring data into or out of the system.
Personal Computer/Advanced Technology (PC/AT): A popular computer design
first introduced by IBM in the early 1980s.
Personal System 2 (PS/2): Computers designed with IBM’s proprietary bus
architecture known as Micro Channel.
Phase-Locked Loop (PLL): A semiconductor device which functions as an electronic
feedback control system to maintain a closely regulated output frequency
from an unregulated input frequency. The typical PLL consists of an internal
phase comparator or detector, a low pass filter, and a voltage controlled
oscillator which function together to capture and lock onto an input
frequency. When locked onto the input frequency, the PLL can maintain a
stable, regulated output frequency (within bounds) despite frequency
variance at the input.
Physical Address: The address or location in memory where data is stored before it is
moved as memory remapping occurs. The physical address is that which
appears on the computer’s address bus when the CPU requests data from a
memory address. When remapping occurs, the data can be moved to a
different memory location or logical address.