NEC DIRECTION SP B - SERVICE 1999, Service And Reference Manual

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10 Glossary
IRQ
Interrupt Request. A signal that, when received by the CPU, makes it stop what it is
going to do something else. An interrupt is a way in which a particular device in a
computer communicates with the CPU. PCs have 16 IRQ lines that can be assigned
to different devices (for example, printers, scanners, modems). No two devices can
have the same IRQ address. See interrupt.
ISA
Industry Standard Architecture. The bus architecture used in the IBM PC/XT and
PC/AT. The AT version of the bus is called the AT bus and has become an industry
standard. The apparent successor is the PCI local bus architecture found in most of
today’s computers. Most modern computers include both an AT bus for slower
devices and a PCI local bus for devices that need better bus performance. In 1993,
Intel and Microsoft introduced a new version of the ISA specification called Plug
and Play ISA. Plug and Play ISA enables the operating system to configure
expansion boards automatically so that users do not need to fiddle with DIP
switches and jumpers. See plug and play.
isochronous
A form of data transmission in which individual characters are only separated by a
whole number of bit-length intervals.
K
kilobyte
(KB) 1024 bytes.
L
L2 cache
Refers to “level 2” or “secondary” cache. A type of cache that resides on the
motherboard except when referring to a Pentium II machine, where it resides on the
CPU module.
LAN
Local Area Network.
M
master
Part of a two-sided communication that initiates commands (to a “slave” that
carries out the commands).
megabyte
(MB) 1,048,576 bytes.
memory
Electronic storage area in a computer that retains information and programs. A
computer has two types of memory: read-only memory (ROM) and random access
memory (RAM).