Operating System introduction, What is operating system, Features, Need, History of OS- Dr. Charu Jain

1. Introduction to Operating System
Charuu

2. Contents
 Todays Topic: Introduction to Operating System
 We will learn
1. What is software?
2. Types of Software
 System s/w, Application s/w
 Examples of system Software
 Operating System, compiler, loader, linker,
Interpreter
3. Examples of Application Software
 Word processors, Spreadsheets, Presentation,
Database systems
4. History of Operating System

3. Software
 Set of programs, anything that can be stored
electronically is Software.
 Software, instructions that tell a computer what to do.
 Software comprises the entire set of programs,
procedures, and routines associated with the operation
of a computer system.

4. Types of Software
 System Software
 Application Software
 Utility Programs

5. System Software:
System software is a term referring to any computer
software which manages and controls the hardware so
that application software can perform a task.
System Software includes the Operating System and all the
utilities that enable the computer to function.
Example:
Operating Systems, Compiler, Loader, Linker, Interpreter.

6. Application Software:
Application Software includes programs that do real work
for user.
Example:
Payroll systems, Inventory Control, Manage student
database, Word Processor, Spreadsheet and Database
Management System etc.,

7. Utility Programs
Utility software helps to manage, maintain and control
computer resources.
Examples of utility programs are antivirus software,
backup software and disk tools.

8. System Software: Language Translator
Source
Languages
Target Languages
‘C’ language ‘C’ language
‘Pascal’ language Machine language
FORTRAN language
C++ language
ADA language
Compiler: A compiler is a program that reads a
program in one language – the source language and
translates into an equivalent program in another
language – the target language.

9. System Software (contd):
Interpreter: An interpreter is a computer
program that translates and executes
instructions written in a computer programming
language line-by-line, unit by unit etc.,
An interpreter needs to be able to analyze, or
parse, instructions written in the source
language.
Example: Lisp systems, etc.,

10. System Software (contd):
Loader: A loader is the part of an operating system that
is responsible for loading programs into memory,
preparing them for execution and then executing them.
The loader is usually a part of the operating system's
kernel and usually is loaded at system boot time and
stays in memory until the system is rebooted, shut down,
or powered off.

11. System Software (contd):
Linker: A linker or link editor is a program that takes
one or more objects generated by compilers and
assembles them into a single executable program.
Linkers can take objects from a collection called a
library. The objects are program modules containing
machine code and information for the linker.
The linker takes care of arranging the objects in a
program's address space.

12. System Software:
Operating System:
 Operating System is a software, which makes a
computer to actually work.
 It is the software the enables all the programs we use.
 The OS organizes and controls the hardware.
 OS acts as an interface between the application
programs and the machine hardware.
 Examples: Windows, Linux, Unix and Mac OS, etc.,

13. Early History: The 1940s
 Operating systems evolved through several phases
 Early computers did not include operating systems.
 All programming was done in absolute machine
language, often by wiring up plugboards to control the
machine's basic functions.
Empty Plugboard

14. Early History: 1950s
 1950s
 The first operating system was introduced in the early
1950's, it was called GMOS and was created by General
Motors for IBM's machine the 701.
 Executed one job at a time
 Included technologies to smooth job-to-job transitions
 Later named as Single-stream batch-processing
systems
 Later they named these machines as mainframes.
 Programs and data submitted consecutively on tape

15. Early History: 1950s

16. The 1960s
 Still batch-processing systems
 Process multiple jobs at once
 Multiprogramming
 One job could use processor while other jobs used
peripheral devices
 Advanced operating systems developed to service
multiple interactive users
 The first version of the Unix operating system was
developed. Written in programming language C, and
available for free during its early years.
 1964
 IBM announced System/360 family of computers

17. The 1960s
 Timesharing systems
 Developed to support many simultaneous interactive users
 Turnaround time was reduced to minutes or seconds
 Time between submission of job and the return of its results
 Real-time systems
 Supply response within certain bounded time period
 Improved development time and methods
 MIT used CTSS system to develop its own successor, Multics
 TSS, Multics and CP/CMS all incorporated virtual memory
 Address more memory locations than actually exist

18. The 1970s
 Primarily multimode timesharing systems
 Supported batch processing, timesharing and real-
time applications
 Fostered by early developments in microprocessor
technology

19. The 1980s
 Decade of personal computers and workstations
 MS-DOS, in full Microsoft Disk Operating System, the
dominant operating system for the personal computer
(PC) throughout the 1980s.
 Computing distributed to sites at which it was needed
 Personal computers proved relatively easy to
learn and use
 Graphical user interfaces (GUI)
 Transferring information between computers via
networks became more economical and practical
 Windows first came to existence in 1985 when a
GUI was created and paired with MS-DOS