Computer hardware provides us
the means of processing and storing information. In order to perform useful
work for us it has been driven by means of software program which specify the
task to be done. Software can be classified into two distinct group - (1)
System Software, (2) Application Software.
System
Software- These software's are designed to provide an environment to
facilitate the writing of application program. Example-Assemblers, loader,
Compiler interpreter, operating system etc.
Application Software - It
consist of collection of program, written by programmer in order to perform
some specific task for users. Example - Word Processor, spread sheets, web
browser etc.
Definition
of Operating System: “Operating system is a system software. It is
a collection of program works between the user and hardware of computer. So
that application program i.e. user program can run in convenient and efficient
manner”.
Operating system is a chief
part of almost every computer system which manages the resources of computer
system. Such as microprocessor, primary and secondary storage devices &
input/output devices. It keeps the information regarding the status of each
resources and decides how long and when to allocate them to specific particular
program and users in order to operate the computer system efficiently and
fairly.
Computer system is divided into
four parts:
(1) Hardware,
(2) Operating System,
(3) Application Software and
(4) Users
There are two main goals of
operating system -
1. Convenience
- The primary goals of operating system is to make computer system easier for
user i.e. operating system makes the interaction between user and hardware
easier.
2. Efficient
- The secondary goal of OS is to allocate the system resources to various
application programs as efficiently as possible.
Functions
of Operating System
1. Processor management, that
is, allocation of processors to different works being done by the computer
system.
2. Memory management, that is,
assignment of main memory and other storage areas to the system programs, user
programs and data.
3. Input/Output management,
that is, proper interaction and allocation of the various input and output
devices when different programs are being executed.
4. File management, that is,
keeping record of files on various storage devices and move all these files
from one device to another. It provides facility to all files to be easily
changed by the use of text editors.
5. Give emphasis on building a job priority
system. That is, it finds out and keeps record of order in which jobs are to be
executed in the computer system.
6. Switching from job to job as
guided by special control statements, automatically.
7. Understand the meaning of
commands and instructions.
8. Making interfacing and
allocation of compilers, assemblers, utility programs, etc to the various users
of the computer system.
9. Building mechanism of data
security and integrity. That is, it stores different programs and data in a way
that they do not communicate with each other and also protects itself from
being damaged by any other user.
10. Generation of traces, error
messages, and other debugging and error-detecting facility.
11. For all users keep record
of internal time clock and log of system usage.
12. Help easy interfacing
between the computer system and the human operator.
Efficiency
of Operating System
The efficiency of an operating
system and the overall performance of a computer installation are judged by a
combination of two main factors. They are:
1. Throughput - It is the total amount of work performed by the
computer system over a given duration of time.
2. Turnaround Time - It is also known as response time and is defined
as the difference of time between the time a user submits his job to the system
for processing and the time he receives output.
Ways
to interact with Operating System (OS)
1. By
means of operating system call in a program.
2. Directly
by means of Operating System Commands.
System
Call
System call provides mechanism
for communication between the operating system and user program (processes).
The set of system call vary from different operating system. Initially, system
calls are written as assembly language instruction. But at present, these are
available as high level languages such as 'C, Pascal etc. System calls are
classified into five categories-
1. Process management system
call.
2. File management system call.
3. Device management system call.
4. Information management
system call.
5. Communication system call.
Types
of System Calls and their respective operation
i)
Process control system call
(a) end, abort
(b) load, execute
(c) create process, terminate
process
(d) get process attributes, set
process attributes
(e) wait for time
(f) wait event, signal event
(g) allocate and free memory
ii)
File management system call
(a) Create file, delete file
(b) open, close
(c) read, write, reposition
(d) get file attributes, set
file attributes
iii)
Device management system call
(a) request device, release
device
(b) read, write, reposition
(c) get device attributes, set
device attributes
(d) logically attach or detach
devices
iv)
Information maintenance system call
(a) get time or date, set time
or date
(b) get system data, set system
data
(c) get process, file, or device
attributes
(d) set process, file, or
device attributes
v)
Communications system call
(a) create, delete
communication connection
(b) send, receive massages
(c) transfer status information
(d) attach or detach remote
devices
System
Commands
The second way to interact directly
with the operating system is with the help of commands. As type commands in MS DOS
(Microsoft Disk Operating System) Command Prompt in order interact with the OS
directly. There are various commands as each has different
use. To know more about command prompt and to get list of commands of windows OS commands– Just Click here!
Posts
0 comments:
Post a Comment