operating systems

1. Operating Systems
Course: MBA-I
Subject: IT For Manager
Unit-3
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2. Operating System Software
• Operating System (OS) – Software that controls the overall operation of a
computer
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3. What is an operating system (OS)?
Operating System Software
Software which manages the overall operation of the computer system including:
• hardware (CPU, RAM, I/O)
• security
• system interface
• application interface
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4. The functions of an operating system
1. Manages and Interacts with Computer
Hardware
2. Provides and Manages System Security
3. Provides the System Interface
4. Provides the Interface for Application
Software
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5. 1. Manages and Interacts with Computer Hardware
• Manages the CPU
- What software programs the
CPU works on and when
• Manages RAM
- What is stored in RAM and
where it is stored
- Virtual memory
- OS will send message when
RAM is full
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6. 1. Manages and Interacts with Computer Hardware (continued)
• Provides the interface for storage
devices and manages how data is
stored on those devices
- in charge of formatting disks
- creates sectors and clusters
- creates F.A.T. or V.T.O.C.
- sends message when disk is
full or there is some other
problem with writing data to
the disk
- virtual memory
- CD-ROM, DVD-ROM
- Flash drive
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7. 1. Manages and Interacts with Computer Hardware (continued)
• Provides the Interface for Input and
Output Devices
– keyboard, mouse, printer,
– device drivers = software
programs which allow the
hardware device to be used by
the operating system and by
application software
Rick Graziani graziani@cabrillo.edu 7

8. 2. Provides and Manages System Security
Single-user Operating Systems
• minimal security
• user has full authority
Server Operating Systems
• login and password capability
• protection of user’s data stored
on the server’s central hard disk
drives
• protection and security for
software programs
Rick Graziani graziani@cabrillo.edu 8

9. 3. Provides the System Interface
System Interface or shell =
the interface between the
user and the computer
Command Line Interface
(CLI)
• Linux, UNIX, DOS, older
OS’s
Graphical User Interface
(GUI)
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10. 4. Provides the Interface for Application Software
• Operating systems are
software
• Operating systems are
designed and developed for a
specific CPU or “family of
CPUs”
– Macintosh OS: Motorola
680xx, PowerPC Gx, Intel
– DOS: Intel CPUs
– Windows 9x and XP: Intel
80386, 80486, and Pentium
CPUs
– Linux: Intel CPUs
– MS NT & 2000: Intel CPUs
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11. 4. Provides the Interface for Application Software
(continued)
• Application software is developed
for an operating system
MS Word for Windows XP
• Windows XP
• Intel CPU
MS Word for the Macintosh
• Macintosh OS X
• Gx CPU or Intel CPU
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12. Order of Development
1. The CPU
2. Other Hardware
Components
3. Operating System
Software
4. Application Software
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13. Types of Operating System

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

15. 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

16. 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

17. 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

18. Common Operating Systems and Their
Differences
• Network Operating System
– UNIX / Linux / MS Windows2000 Server
• Desktop Operating System
– MS Windows 9X/Me / Mac OS / DOS
• Mobile Operating System
– Palm OS and Pocket PC

19. Different Features of Operating System

20. Type of Operating System
• Batch processing
• Real time processing
• Time sharing processing

21. Batch processing
• Jobs, together with input data, are fed into
the system in a batch.
• The jobs are then run one after another.
• No job can be started until previous job is
completed
Batch Processing

22. Real time processing
• immediate response is needed.
• For example
– anti-missile defense system
– airplane landing control system
– interrupt error in computer system

23. Time sharing processing
• Each user is given a time slice to interact
with the CPU.
• The size of the time slice will depend on the
system.
• Each user is served in sequence.

24. Special Features of OS
• multi-tasking
• multi-programming
• parallel processing
• buffering
• spooling

25. Multi-tasking
• to handle 2 or more programs at the same time
from a single user ‘s perception
– CPU can only perform one task at a time, however,
it runs so fast that 2 or more jobs seem to execute
at the same time
Multi-Tasking

26. Multi-programming
• 2 or more programs store in the main memory
at the same time
• when one job reeds to wait (e.g. I/O operation),
CPU switch to another job to execute
• when the first job finishes waiting, CPU will
get back the first job to execute

27. Parallel Processing
• use 2 or more CPUs to handle jobs
• computer networking
Job 1 Job 2
Job 3
Job 4
Job 1
Job 2
Job 3
Job 4
CPU 1 CPU 2 CPU 1
time time
without multiprocessing
with multiprocessing

28. Buffering
• A temporary storage area (buffers) to read data
from input device or send data to the output
device
• keep CPU busy
– because I/O operation is slow

29. What is Database Management
System(DBMS)?
• A database management system (DBMS) is a
collection of programs that enables you
to store, modify, and extract information from
a database. There are many different types of
DBMSs, ranging from
small systems that run on personal
computers to huge systems that run
on mainframes.

30. APPLICATION
• Banking: For customer ,informaion,account,and loans, and transaction.
• Airline: For reservation and schedule information. Airline were
among the first to use database in a geographically distributed
manner terminals situated around the world accessed the central
database system through phone lines and other data network.
• Universities: For students information, course registration, and
grades.
• Credits card transaction: For purchases on credits cards and
generation of monthly statements.
• Sales: For customer, product, and purchase information.
• Human resources: For information about employees, salaries,
payroll taxes and benefits, and for generation of paychecks.

31. Advantage of DBMS
1. Controlling Data Redundancy
2. Data Consistency:
3. Data Sharing:
4. Data Integration:
5. Integrity Constraints:
6. Data Security:
7. Data Atomicity:
8. Database Access Language:
9. Development of Application:
10. Creating Forms:
11. Report Writers:
12. Control Over Concurrency:
13. Backup and Recovery Procedures:
14. Data Independence:
15. Advanced Capabilities:

32. Disadvantage of DBMS
1. Cost of Hardware & Software
2. Cost of Data Conversion
3. Cost of Staff Training
4. Appointing Technical Staff
5. Database Failures

33. Data Model of DBMS
Types of Data Models
• Entity-Relationship data model
• Relational Model
• Object oriented data Model
• Hierarchical data model

34. E-R model
• The entity-relationship (E-R) data model is
based on a perception of a real world that
consists of a collection of basic objects, called
entities, and of relationships among these
objects. An entity is a “thing” or “object” in
the real world that is distinguishable from
other objects.
• For example, each person is an entity, and
bank accounts can be considered as entities.

35. E-R model
ER Model is based on:
Entities and their attributes
Relationships among entities

36. E-R model
• Entity
• An entity in ER Model is real world entity, which has some
properties called attributes. Every attribute is defined by its
set of values, called domain.
• For example, in a school database, a student is considered as
an entity. Student has various attributes like name, age and
class etc.
• Relationship
The logical association among entities is called relationship.
Relationships are mapped with entities in various ways.
Mapping cardinalities define the number of association
between two entities.

37. Keys
Keys are very important part of Relational database. They are used to
establish and identify relation between tables. They also ensure that
each record within a table can be uniquely identified by combination
of one or more fields within a table.
• Super Key
It defined as a set of attributes within a table that uniquely identifies
each record within a table. Super Key is a superset of Candidate key.
• Candidate Key
it is defined as the set of fields from which primary key can be
selected. It is an attribute or set of attribute that can act as a primary
key for a table to uniquely identify each record in that table.

38. Primery Key
It is a candidate key that is most appropriate to become main key of the table. It is a key
that uniquely identify each record in a table

39. Composite Key
• that consist of two or more attributes that uniquely
identify an entity occurance is called Composite key. But
any attribute that makes up the Composite keyis not a
simple key in its own Secondary or Alternative key.The
candidate key which are not selected for primary key are
known as secondary keys or alternative keys

40. Reference
Book Reference
1. Operating System Concepts by Abraham Silberschatz, Peter B. Galvin, Greb
Gagne
2. Operating System Concepts by James Lautor Peterson, Abrahamautor Silbeschatz
3. Database System Concepts by Abraham Silberschatz, Henry F. Korth,
S.Sudarshan
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