Page 10 - DCAP403_Operating System

Unit 1: Introduction to Operating System

An effective operating system should accomplish the following functions: Notes

1. Should act as a command interpreter by providing a user friendly environment.
2. Should facilitate communication with other users.

3. Facilitate the directory/file creation along with the security option.
4. Provide routines that handle the intricate details of I/O programming.
5. Provide access to compilers to translate programs from high-level languages to machine
language.
6. Provide a loader program to move the compiled program code to the computer’s memory
for execution.
7. Assure that when there are several active processes in the computer, each will get fair and
non-interfering access to the central processing unit for execution.
8. Take care of storage and device allocation.

9. Provide for long term storage of user information in the form of fi les.
10. Permit system resources to be shared among users when appropriate, and be protected
from unauthorised or mischievous intervention as necessary.

Figure 1.2: Abstract View of the Components of a Computer System

User 1 User 2 User 3 User n

Compiler Assembler Text editor Database
system
Application programs

Operating System

Computer hardware

Though systems programs such as editors and translators and the various utility programs (such
as sort and file transfer program) are not usually considered part of the operating system, the

operating system is responsible for providing access to these system resources.
The abstract view of the components of a computer system and the positioning of OS is shown
in the Figure 1.2.

Task “Operating system is a hardware or software”. Discuss.

1.2 History of Computer Operating Systems

Early computers lacked any form of operating system. The user had sole use of the machine and
would arrive armed with program and data, often on punched paper and tape. The program
would be loaded into the machine, and the machine would be set to work until the program
completed or crashed. Programs could generally be debugged via a front panel using switches
and lights. It is said that Alan Turing was a master of this on the early Manchester Mark I machine,

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