Network Card User Manual

Glossary 31

Glossary

Address - A specific location in memory, designated either numerically or by a symbolic

name.

Asynchronous Data Transfer - A method of transmission which does not require a common

clock, but separates fields of data by stop and start bits. It is slower than synchronous data

transfer.

BIOS - Basic Input/Output System. Software that provides basic read/write capability. Usually

kept as firmware (ROM based). The system BIOS on the mainboard of a computer is used to

boot and control the system. The SCSI BIOS on your host adapter acts as an extension of the

system BIOS.

Bit - A binary digit. The smallest unit of information a computer uses. The value of a bit (0 or

1) represents a two-way choice, such as on or off, true or false, and so on.

Bus - A collection of unbroken signal lines across which information is transmitted from one

part of a computer system to another. Connections to the bus are made via taps on the lines.

Bus Mastering - A high-performance way to transfer data. The host adapter controls the

transfer of data directly to and from system memory without bothering the computer’s

microprocessor. This is the fastest way for multitasking operating systems to transfer data.

Byte - A unit of information consisting of eight bits.

Chain - A topology in which every processor is connected to two others, except for two end

processors that are connected to only one other.

CISPR - A special international committee on radio interference (Committee, International

and Special, for Protection in Radio). B-2 Glossary of Terms and Abbreviations

Configuration - Refers to the way a computer is set up; the combined hardware components

(computer, monitor, keyboard, and peripheral devices) that make up a computer system; or

the software settings that allow the hardware components to communicate with each other.

CPU - Central Processing Unit. The “brain” of the computer that performs the actual

computations. The term Micro Processor Unit (MPU) is also used.

DMA - Direct Memory Access. A method of moving data from a storage device directly to

RAM, without using the CPU’s resources.

DMA Bus Master - A feature that allows a peripheral to control the flow of data to and from

system memory by blocks, as opposed to PIO (Programmed I/O) where the processor is in

control and the flow is by byte.

Device Driver - A program that allows a microprocessor (through the operating system) to

direct the operation of a peripheral device.

Differential - A hardware configuration for connecting SCSI devices. It uses a pair of lines

for each signal transfer (as opposed to single-ended SCSI which references each SCSI signal

to a common ground).

Dword - A double word is a group of 4 consecutive bytes or characters that are stored, addressed,

transmitted, and operated on as a unit. The lower two address bits of the least significant byte

must equal zero in order to be dword aligned.

EEPROM - Electronically-Erasable Programmable Read Only Memory. A memory chip

typically used to store configuration information. See NVRAM.