HP I Dual Channel Ultra160 SCSI Host Adapter A6829A manual Glossary

Glossary

A

address A specific location in memory, designated either numerically or by a symbolic name.

asynchronous data transfer One of the ways data is transferred over the SCSI bus. It is slower than synchronous data transfer.

B

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.

Boot Console Handler (BCH) Provides, among other things, the reading and setting of SCSI parameters without the OS running.

bus A collection of wires in a cable or copper traces on a circuit board used to transmit data, status, and control signals. EISA, PCI, and SCSI are examples of buses.

bus mastering A high-performance way to transfer data. The host bus adapter controls the transfer of data directly to and from system memory without bothering the computer’s microprocessor. This is the fastest way for multi-tasking operating systems to transfer data.

byte A unit of information consisting of eight bits.

C

central processing unit (CPU) The “brain” of the computer that performs the actual computations. The term Micro Processor Unit (MPU) is also used.

chain A topology in which every device is connected to two others, except for two-end devices that are connected to only one other.

Committee, International and Special, for Protection in Radio (CISPR) An international committee on radio frequency interference.

configuration Refers to the way a computer is set up; the combined hardware components (computer, monitor, key board, and peripheral devices) that make up a computer system; or the software settings that allow the hardware components to communicate with each other.

Cyclic Redundancy Check (CRC) 32-bit scheme (referred to as CRC-32) included in Ultra160 that ensures complete integrity of the transferred data. CRC is guaranteed to detect all single bit errors, any two bits in error, or any combination of errors within a single 32-bit range.

D

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).

direct memory access (DMA) A method of moving data from a storage device directly to RAM, without using the CPU’s resources.

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