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EPC
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Glossary
H A R D W A R E
R E F E R E N C E
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.
POST
(Power On Self Test) A diagnostic routine which a computer runs at power up. Along
with other testing functions, this comprehensive test initializes the system chipset and
hardware, resets registers and flags, performs ROM checksums, and checks disk drive
devices and the keyboard interface.
PQFP
(Plastic Quad Flat Pack) A popular package design for integrated circuits of high
complexity.
program
A set of instructions a computer follows to perform specific functions relative to user
need or system requirements. In a broad sense, a program is also referred to as a
software application, which can actually contain many related, individual programs.
PS/2
(Personal System 2) Computers designed with IBM’s proprietary bus architecture
known as Micro Channel.
PSB
Processor Side Bus.
RAM
(Random Access Memory) Memory in which the actual physical location of a memory
word has no effect on how long it takes to read from or write to that location. In other
words, the access time is the same for any address in memory. Most semiconductor
memories are RAM.
RAS
(Row Address Strobe) An input signal to an internal DRAM latch register specifying the
row at which to read or write data. The DRAM requires a row address and a column
address to define a memory address. Since both parts of the address are applied at the
same DRAM inputs, use of row addresses and column addresses in a multiplexed array
allows use of half as many pins to define an address location in a DRAM device as
would otherwise be required.
real mode
The operational mode of Intelx86 CPUs that uses a segmented, offset memory
addressing method. These CPUs can address 1 MB of memory using real mode.
real mode
Address
A memory address composed of two 16-bit values: a segment address and an offset
quantity. A real mode address is constructed by shifting a segment address 4 bits to the
left and then adding the offset value. A real mode address is a physical address.
reflashing
The process of replacing a BIOS image, in binary format, in the flash boot device.
register
An area typically inside the microprocessor where data, addresses, instruction codes,
and information on the status on various microprocessor operations are stored.
Different types of registers store different types of information.
reset
A signal delivered to the microprocessor by the control bus, which causes a halt to
internal processing and resets most CPU registers to 0. The CPU then jumps to a
starting address vector to begin the boot process.
RFA
(Resident Flash Array) The RFA represents flash memory that is resident on the
hardware platform that is utilized for OS or application purposes.
ROM
(Read Only Memory) A broad class of semiconductor memories designed for
applications where the ratio of read operations to write operations is very high.
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