This utility program facilitates the backing-up of disk. Back-up means duplicating the disk information so that in case of any damage or data-loss this backed-up data can be used.

An explict, inherent feature activated or excited by an external stimulus to perform a function at a specified level of performance until terminated by external commands, timed completion or resource depletion is called as capability.

Performance is a quantitative measure characterising a physical or functional attribute relating to the execution of an operation or function.

Every system, product and service has a life cycle that depicts its level of maturity is called as system life cycle.

Operating characteristics describe system features related to usability, survivability and performance for a prescribed operating environment.

Function is an operation, activity, process or action performed by a system element to achieve a specific objective within a prescribed set of performance limits.

Characteristics refer to the behavioral and physical qualities that uniquely identify each system.

System definition phase begins with recognition by the user that a new system or upgrade to an existing system, product or service is required to satisfy an operational need.

Mission system roles are performed by system that are assigned specific tasks to deliver product and services that achieve performance based outcome objectives.

Operationally suitability characterizes hoe well the system or product is, suited to a user's specific application in a given operating environment and integrates and performs within the user's existing system.

Changing all the bits that are 1 to 0 and all the bits that are 0 to 1 is known as 1's complement.

System disposal phase consists of those activities required to phase out as existing or legacy system from active duty.

The microprocessor uses flags to test data conditions.

An instruction is a command to the microprocessor to perform a given task on a specified data.

Data bus carries data in binary form between microprocessor and other external unit.

A sequence of instructions telling the computer what to do is called a program.

A process is created to execute a command.

Microprocessor  uses program counter to sequence the execution of the instruction.

Code files can obtain a symbol table - a table indicating the names of all functions and global variables, and the virtual addresses that correspond to.

Operating System is a program that controls the execution of an application program and acts as an interface between the user and the computer hardware.

Virtual memory is a program that controls the execution of an application program and acts as an interface between the user and the computer hardware.

Translation lookaside buffer is used to speed up paging and avoid frequent access to main memory.

The part of the operating system which manages the primary memory of the computer is called as Memory manager.

The condition of splitting primary memory into segments as the memory is allocated is known as fragmentation.

Mainframe Operating System are large centralized computers and at one time they provide bulk of business computing through time sharing.