The document discusses operating systems and their functions. It defines an operating system as a collection of programs that control computer resources and act as an interface between users and hardware. The main functions of an operating system are device configuration, memory management, file management, and providing an interface for applications. The document also outlines the evolution of operating systems from early batch processing systems to modern personal computing and distributed systems. Finally, it distinguishes between single-user and multi-user operating systems.

1. Operating System

2. Architecture of Computer System
Hardware
Operating System (OS)
Programming Language (e.g. PASCAL)
Application Programs (e.g. WORD, EXCEL)

3. • System Software- Performs essential operation tasks
– Operating system
– Utility programs
• Application Software - Performs specific tasks for users
– Business application
– Communications application
– Multimedia application
– Entertainment and educational software
• Driver Programs (Device Driver)
– small program that allows a specific input or output
device to communicate with the rest of the computer
system
System Software, Application
Software and Driver Programs

4. Operating System
• a collection of programs which control the
resources of a computer system
• written in low-level languages (i.e.
machine-dependent)
• an interface between the users and the
hardware
• when the computer is on, OS will first load
into the main memory

5. Operating
System
Device configuration
Controls peripheral devices connected to the computer
File management
Transfers files between main memory and secondary
storage, manages file folders, allocates the secondary
storage space, and provides file protection and
recovery
Memory management
Allocates the use of random access memory (RAM) to
requesting processes
Interface platform
Allows the computer to run other applications
Basic functions of the operating
system

6. Other function of Operating
System
• best use of the computer resources
• provide a background for user’s programs
to execute
• display and deal with errors when it
happens
• control the selection and operation of the
peripherals
• act as a communication link between users
• system protection

7. Evolution of OS
Major
Phases
Technical
Innovations
Operating
Systems
Open Shop The idea of OS IBM 701 open shop
(1954)
Batch
Processing
Tape batching,
First-in, first-out
scheduling.
BKS system (1961)
Multi-
programming
Processor multiplexing,
Indivisible operations,
Demand paging,
Input/output spooling,
Priority scheduling,
Remote job entry
Atlas supervisor
(1961),
Exec II system (1966)

8. Evolution of OS
Timesharing Simultaneous user
interaction,
On-line file systems
Multics file system
(1965),
Unix (1974)
Concurrent
Programming
Hierarchical systems,
Extensible kernels,
Parallel programming
concepts, Secure parallel
languages
RC 4000 system (1969),
13 Venus system
(1972),
14 Boss 2 system
(1975).
Personal
Computing
Graphic user interfaces OS 6 (1972)
Pilot system (1980)
Distributed
Systems
Remote servers WFS file server (1979)
Unix United RPC (1982)
24 Amoeba system
(1990)

9. Types of OS:
Operating System can also be classified as,-
• Single User Systems
• Multi User Systems

10. Single User Systems:
• Provides a platform for only one user at a
time.
• They are popularly associated with Desk
Top operating system which run on
standalone systems where no user accounts
are required.
• Example: DOS

11. Multi-User Systems:
• Provides regulated access for a number of users by
maintaining a database of known users.
• Refers to computer systems that support two or more
simultaneous users.
• Another term for multi-user is time sharing.
• Ex: All mainframes and are multi-user systems.
• Example: Unix