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IRQ (Interrupt Request): an electronic request that runs from a hardware
device to the CPU. The interrupt controller assigns priorities to incoming
requests and delivers them to the CPU. It is important that there is only one
device hooked up to each IRQ line; doubling up devices on IRQ lines can lock
up your system. Plug-n-Play operating systems can take care of these details
for you.
Latency: the amount of time that one part of a system spends waiting for
another part to catch up. This occurs most commonly when the system sends
data out to a peripheral device and has to wait for the peripheral to spread
(peripherals tend to be slower than onboard system components).
NVRAM: ROM and EEPROM are both examples of Non-Volatile RAM, memory
that holds its data without power. DRAM, in contrast, is volatile.
Parallel port: transmits the bits of a byte on eight different wires at the same
time.
PCI (Peripheral Component Interconnect): a 32 or 64-bit local bus (data
pathway) which is faster than the ISA bus. Local buses are those which operate
within a single system (as opposed to a network bus, which connects multiple
systems).
PCI PIO (PCI Programmable Input/Output) modes: the data transfer modes
used by IDE drives. These modes use the CPU for data transfer (in contrast,
DMA channels do not). PCI refers to the type of bus used by these modes to
communicate with the CPU.
PCI-to-PCI bridge: allows you to connect multiple PCI devices onto one PCI
slot.
PM timers (Power Management timers): software timers that count down the
number of seconds or minutes until the system times out and enters sleep,
suspend, or doze mode.
PnP (Plug-n-Play): a design standard that has become ascendant in the
industry. Plug-n-Play devices require little set-up to use. Devices and operating
systems that are not Plug-n-Play require you to reconfigure your system each
time you add or change any part of your hardware.
PXE (Preboot Execution Environment): one of four components that together
make up the Wired for Management 2.0 baseline specification. PXE was
designed to define a standard set of preboot protocol services within a client
with the goal of allowing networked-based booting to boot using industry
standard protocols.
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