1. Computer Lab
 An Operating System

2. Definition
An operating system is an integrated set of
programs that controls the resources (cpu, memory,
input/output devices etc. ) of a computer system and
provides its users with an interface.
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3. The OS is the computers master control
program. The Os provides us with commands that
enables us to interact with the pc. When we issue
a command, the OS translate it into code that the
machine can use.

4.  Some popular operating system are-
Unix, Ms-Dos, Microsoft Windows, Microsoft
Windows NT, Linux.

5. Functions of the operating
System
 1. It displays the on-screen elements
which we interact.
 2. It loads programs into the computers memory
so that we can use them.
 3. It coordinates how programs work with the
computers hardware and other software.
 4. OS manages the way how information is stored
on and retrieved from disk.

6. Types of operating system;
1. Real time operating system,
2. Single user Single tasking OS,
3. Single user MultitaskingOS,
4. Multi user Multitasking OS.

7. Real time operating system
A real time operating system is a very fast, relatively
small OS.
It is needed to run real-time applications.
It may support multiple simultaneous tasks or it may
support only single tasking.
Real time applications are needed to run medical
diagnostics equipment, life-support system, scientific
instruments & industrial system.

8. Single user/single tasking operating
system
An operating system that allows a single user to perform
just one task at a time is a Single user-single tasking
operating system.
To a user a task is a function such as printing a document
, writing a file to disk, editing a file or downloading a
file from a network server.
MS-DOS is an example of a single-tasking OS

9. Single user/multitasking Operating
system
A single user-multitasking operating system is one that
allows a single user to perform two or more functions
at once.
The most commonly used personal computers usually
run such Oss, including Microsoft Windows and
Macintosh operating system.

10. Multi user/ Multi tasking Operating
system
A multi user-multi tasking operating system is an
operating system that allows multiple users to use
programs that are simultaneously running on a single
network server called terminal server.
In a multi user-multi tasking operating system
environment all or most of the computing occurs at
the server.
Examples of multi user- multi tasking Oss include
UNIX, VMS

11. User Interface
When we work on a computer we see and use a set of
items on the screen
Taken together, these items are called the user interface.

12. The two most common types of user interface are:
 Graphical user interface and
 Command line user interfaces.

13. Prepared by:
Md. Aziz ullah
1229CSE00234
Dept. of CSE
Manarat International University
Gulshan-2, Dhaka-1212, Bangladesh.