Rockwell Automation 1770-M12 Mass Storage Systems - Manual (Page 69)

Glossary
Appendix E
EĆ4
Off–line: Equipment or devices that are not connected to or in direct
communication with the central processing unit. Contrast with on–line.
On–line: Equipment or devices that are connected to or directly communicate
with central processing unit. Contrast with off–line.
Open System: Any system that interacts with its environment through input
and output.
Operating System: A software system that controls the operation of a
processor system by providing for input/output, allocation of memory space, or
translation of programs.
Peripheral: Pertaining to equipment that is attached to the programmable
controller system to augment or make it possible to use the central processing
unit, including input/output, communications, and secondary storage devices.
Physical File: The data contained on one storage device like a magnetic tap or
magnetic disk.
Record: A group of data items that are stored together and/or used together in
processing. A collection of related data items treated as a unit. See also file.
Recording Density: The amount of data that can be stored in a specific section
or area. For example, on magnetic tape, recording density is often expressed in
terms of the number of bytes or characters of data that can be stored in an inch
of tape.
Sector: A pie–shaped section on the surface of a magnetic disk.
Software: The term applied to computer programs that control the processing
of data in a computer system. This may include either user–written or
commercially prepared programs like translators, utility routines, or database
management systems. Contrast with hardware.
Subsystem: A part of a larger system having all of the properties of a system in
its own right. A system with another system.
System: A set of one or more PCs, I/O devices and modules, computers, the
associates software, peripherals, terminals, and communication networks, that
together, provide a means of performing information processing for controlling
machines or processes.
Track: The recording path on a rotating surface. A path for recording one
channel of information on a magnetic tape, drum, or other magnetic recording
medium. A part of a secondary storage device that is accessed by one read/write
head.
Twinaxial Cable: A single shielded twisted–pair cable which has low–loss
signal transmission and high noise immunity.