De-allocates the resources.
Other Important Activities
Following are some of the important activities that an Operating System
Security − By means of password and similar other techniques, it
prevents unauthorized access to programs and data.
Control over system performance − Recording delays between request
for a service and response from the system.
Job accounting − Keeping track of time and resources used by various
jobs and users.
Error detecting aids − Production of dumps, traces, error messages,
and other debugging and error detecting aids.
Coordination between other softwares and users − Coordination and
assignment of compilers, interpreters, assemblers and other software
to the various users of the computer systems.
1.2 Single processor, multiprocessor and clustered
systems - Overview
Computer architecture means design or construction of a computer. A
computer system may be organized in different ways. Some computer
systems have single processor and other have multiprocessors. So
computer systems categorized in these ways.
Single Processor Systems
Some computers use only one processor such as microcomputers. On a
single processor system, there is only one CPU that perform all the activities
in the computer system, However, most of these systems have other
special purpose processors, such as I/O Processor that move data rapidly
among different components of the computer system. These processors
execute only a limited system programs and do not run the user program.
So we define single processor systems as “ A system that has only one
general purpose CPU, is considered as single processor system.
Some systems have two or more processors. These systems are also known
as parallel systems or tightly coupled systems. Mostly the processors of