Page 22 - DCAP403_Operating System

Unit 2: Operation and Function of Operating System

5. File Management Notes
6. Protection
7. Networking Management

8. Command Interpretation.
Process Management

The CPU executes a large number of programs. While its main concern is the execution of user
programs, the CPU is also needed for other system activities. These activities are called processes.
A process is a program in execution. Typically, a batch job is a process. A time-shared user
program is a process. A system task, such as spooling, is also a process. For now, a process may
be considered as a job or a time-shared program, but the concept is actually more general.
The operating system is responsible for the following activities in connection with processes
management:
1. The creation and deletion of both user and system processes

2. The suspension and resumption of processes.
3. The provision of mechanisms for process synchronization
4. The provision of mechanisms for deadlock handling.

Memory Management

Memory is the most expensive part in the computer system. Memory is a large array of words or
bytes, each with its own address. Interaction is achieved through a sequence of reads or writes of

specific memory address. The CPU fetches from and stores in memory.
There are various algorithms that depend on the particular situation to manage the memory.

Selection of a memory management scheme for a specific system depends upon many factors, but
especially upon the hardware design of the system. Each algorithm requires its own hardware
support.
The operating system is responsible for the following activities in connection with memory
management.

1. Keep track of which parts of memory are currently being used and by whom.
2. Decide which processes are to be loaded into memory when memory space becomes
available.
3. Allocate and deallocate memory space as needed.

Secondary Storage Management

The main purpose of a computer system is to execute programs. These programs, together with
the data they access, must be in main memory during execution. Since the main memory is too
small to permanently accommodate all data and program, the computer system must provide
secondary storage to backup main memory. Most modem computer systems use disks as
the primary on-line storage of information, of both programs and data. Most programs, like
compilers, assemblers, sort routines, editors, formatters, and so on, are stored on the disk until
loaded into memory, and then use the disk as both the source and destination of their processing.
Hence the proper management of disk storage is of central importance to a computer system.

LOVELY PROFESSIONAL UNIVERSITY 15