Introduction to mis

Classification of Computers
Types of Computers
1. Analog Computers
Analog computers are used to process continuous data. Analog computers
represent variables by physical quantities. Thus any computer which solve
problem by translating physical conditions such as flow, temperature,
pressure, angular position or voltage into related mechanical or electrical
related circuits as an analog for the physical phenomenon being investigated
in general it is a computer which uses an analog quantity and produces analog
values as output. Thus an analog computer measures continuously. Analog
computers are very much speedy. They produce their results very fast. But
their results are approximately correct. All the analog computers are special
purpose computers.

2. Digital Computers
Digital computer represents physical quantities with the help of digits or numbers.
These numbers are used to perform Arithmetic calculations and also make logical
decision to reach a conclusion, depending on, the data they receive from the user.

3. Hybrid Computers
Various specifically designed computers are with both digital and analog
characteristics combining the advantages of analog and digital computers when
working as a system. Hybrid computers are being used extensively in process
control system where it is necessary to have a close representation with the physical
world.
The hybrid system provides the good precision that can be attained with analog
computers and the greater control that is possible with digital computers, plus the
ability to accept the input data in either form.

1. Super Computers
Large scientific and research laboratories as well as the government organizations
have extra ordinary demand for processing data which required tremendous
processing speed, memory and other services which may not be provided with any
other category to meet their needs. Therefore very large computers used are called
Super Computers. These computers are extremely expensive and the speed is
measured in billions of instructions per seconds.

3. Mini Computers
Mini computers are smaller than mainframes, both in size and other facilities such
as speed, storage capacity and other services. They are versatile that they can be
fitted where ever they are needed. Their speeds are rated between one and fifty
million instructions per second (MIPS). They have primary storage in hundred to
three hundred megabytes range with direct access storage device.

4. Micro Computers
These are the smallest range of computers. They were introduced in the early 70’s
having less storing space and processing speed. Micro computers of todays are
equivalent to the mini computers of yesterday in terms of performing and
processing. They are also called “computer of a chip” because its entire circuitry is
contained in one tiny chip. The micro computers have a wide range of applications
including uses as portable computer that can be plugged into any wall.

Input Devices
 Input Devices: devices
that input information
into the computer such
as a keyboard, mouse,
scanner, and digital
camera.

Output Devices
 Output: devices that
output information
from the computer such
as a printer and
monitor.

Central Processing Unit
 CPU (Central Processing Unit) also called the
Microprocessor or “The Brain” of the Computer.
 Processor speed: The speed at which a
microprocessor executes instructions. This is usually
measured in megahertz (MHz).
 Brands of Processors include:
 Pentium
 Celeron
 MAC
 AMD
 Cyrix

Central Processing Unit
 Computer chip: also called the
microprocessor may contain an
entire processing unit.
 Computer chips contain millions
of transistors. They are small
pieces of semi-conducting
material (silicon).
 An integrated circuit is embedded
in the silicon. Computers are made
of many chips on a circuit board.

Data Storage Devices
 The hard-drive is a mechanical
storage device typically located
internally.
 Fast recording and recovery of
data
 Large storage capacity
 Magnetic
 Primary storage device for data
and programs
 Speed is measured in R.P.M.’s

Data Storage Devices (cont’d)
 CD-ROM (compact disk read
only memory)
 Approximately 600 to 700
megabyte of storage
 An optical device read by
a diode laser

Data Storage Devices (cont’d)
 Floppy diskette is magnetic
storage device for small
amounts of data (1.44MB).
 FLASH drive is a compact
and portable electronic
storage device.
 USB (plug and play)
supported

Computer Memory
 Computer memory is binary (0 or 1) (on or off).
 The byte is the standard unit of measurement.
 A byte is composed of 8 bits (binary digits).
 Typical units of measurement:
 1 KB (kilobyte) = 1000 bytes
 1 MB (megabyte) =1000 kilobytes or 1 million bytes
 1 GB (gigabyte) =1000 megabytes or 1 billion bytes

Computer Memory
 RAM (random access memory)
stores data that is processing.
This type of memory is erased
when the computer is turned
off.
 ROM (read only memory)
contains special instructions for
the computer to operate.
 Cache memory increases the
speed of the processor by
recording and anticipating
instructions.

Graphic User Interface (GUI)
 GUI (Graphic User Interface) is a set of images
and icons seen on the desktop used to operate
a program.
 The GUI makes the programs loaded on the
computer easier to access and use. Basic
Windows GUI
 Icons are small pictures that represent files,
commands, or windows.
 Windows is a GUI operating system unlike
UNIX, which uses text commands.

Video Cards
 Video cards plug into the
motherboard and are used to
display video.
 VRAM is video memory that
enhances the refreshment rate
of the image.
 Video cards have chipsets that
can increase the speed of video
display.

Ports and Peripherals
Ports are an interface between the computer and another
peripheral device such as a disk drive, mouse, printer, modem,
monitor, camera, FLASH drive or keyboard.
Examples:
Serial
Parallel
hot-wire
USB

Ports and Peripherals
Peripherals are devices that
plug into a computer and are
not housed internally.
Examples:
Printers
Scanners
Cameras

Resolution
 Resolution refers to the
number of pixels (picture
elements) in the monitor
image.
 Increased resolution uses
more computer resources but
increases the visual clarity of
the display.

Resolution
 Screen resolution is measured in pixel per inch
(ppi), and printer resolution is measured in dots
per inch (dpi).
 Computer screen resolution is approximately 72
ppi.
Width x Height (Pixels) Video Display
640 x 480 Low Resolution
800 x 600 Medium Resolution
1600 x 1200 High Resolution

LAN and WAN
 LAN: are networks usually in the
same company or building. The
Local Area Network is
connected via telephone lines or
radio waves. Most LANs connect
workstations.
 WAN: are systems of LANs that
are connected. (Wide-area
network)

Bandwidth and Baud Rate
 Bandwidth is how much
information can be carried in
a given time period (usually a
second) over a wired or
wireless communications
link.
 Baud rate is the rate at which
information is transferred in
a communication channel.

Multitasking and Multiprocessing
 Multitasking is the ability to
execute more than one task
(program) at the same time.
Only one CPU is used but
switches from one program to
another.
 In multiprocessing, more than
one CPU is used to complete a
task. Example: network
rendering.

Multimedia
 Multimedia software programs
include sound, pictures, video,
text, and hypertext to create
presentations.
Software includes:
PowerPoint
Macromedia Director
FLASH

File Management
 Different programs have different file extensions.
 Naming files - avoid the following characters in naming files:
Examples:
 @
 *
 .
 Understand the parts of a path name.
Example: C:SciVismovie.avi
Drive designator Directory or folder File name File extension

File Management
 Saving files - know the difference
between “save” and “save as”. “Save” will
save the open document over the saved
document while “save as” creates a new
document if you rename the document.
Save often so work will not be lost.
 Exporting – converts a native format to a
non-native file format used in various
software programs. In vector programs,
file types may be exported.

File Management
 Merging files - in 3D
graphics, bringing an
outside file into an open
file (another name for this
may be loading or
replacing objects in the
workspace).
 Importing files - bringing a
converted non-native
format file into an open
file.

Introduction to Networks
 A network consists of two or more entities or objects
sharing resources and information.
 A computer network consists of two or more
computing devices connected to each other to share
resources and information.
 The network becomes a powerful tool when computers
communicate and share resources with other
computers on the same network or entirely distinct
networks.

 Computers on a network can act as a client or a server.
 A client is a computer that requests for resources.
 A server is a computer that controls and provides
access to resources.

 Data is a piece of information.
 The computing concept ‘hierarchy of data’ is used when
planning a network.
 It is essential to maintain a hierarchy of data to manage and
control resources among computers.
 Network access to data must be evaluated carefully to avoid
security issues.

Need for Networks
 A computer that operates independently from other
computers is called a stand-alone computer.
 The process of printing or transferring data from one
system to another using various storage devices is
called sneakernet.

Need for Networks
 Enhance communication.
 Share resources.
 Facilitate centralized management.

Enhance Communication
 Computer networks use electronic mail (e-mail) as the
choice for most of the communication.
 By using networks, information can be sent to a larger
audience in an extremely fast and efficient manner.

Share Resources
 A copy of data or application stored at a single central
location is shared over a network.
 Computer peripheral devices, referred to as additional
components, can be attached to a computer and be
shared in a network.

 Peripheral devices include faxes, modems, scanners,
plotters, and any other device that connects to the
computers.
 Equipments having common requirements can be
shared in order to reduce maintenance cost.
Share Resources

Share Resources
 Important data can also be stored centrally to make it
accessible to users, thereby saving storage space on
individual computers.
 Computer applications, which take up a considerable
amount of storage space, can be installed centrally on
the network, saving storage space.

Facilitate Centralized Management
 Networks are used to assist in management tasks
associated with their own operation and maintenance.
 Using networks results in increased efficiency and a
resultant reduction in maintenance costs.

Facilitate Centralized Management
Software:
 Software is a set of instructions or programs that control
the operation of a computer.
 Software can be installed at a central location using
servers, where the installation files are made accessible
over the network.

Classification of Networks
 Classification by network geography.
 Classification by component roles.

Classification by Network
Geography
 Networks are frequently classified according to the
geographical boundaries spanned by the network
itself.
 LAN, WAN, and MAN are the basic types of
classification, of which LAN and WAN are frequently
used.

Local area network (LAN):
 A LAN covers a relatively small area such as a classroom,
school, or a single building.
 LANs are inexpensive to install and also provide higher
speeds.
Geography

Local area network
Geography

Metropolitan area network (MAN):
 A MAN spans the distance of a typical metropolitan city.
 The cost of installation and operation is higher.
 MANs use high-speed connections such as fiber optics
to achieve higher speeds.
Geography

Metropolitan area network
Geography

Wide area network (WAN):
 WANs span a larger area than a single city.
 These use long distance telecommunication networks
for connection, thereby increasing the cost.
 The Internet is a good example of a WAN.
Geography

Wide area network
Geography

Classification by Component Roles
 Networks can also be classified according to the roles
that the networked computers play in the network’s
operation.
 Peer-to-peer, server-based, and client-based are the
types of roles into which networks are classified.

Data vs. Information
 Data are raw facts
 Information is the result of processing raw data to
reveal meaning
 Information requires context to reveal meaning
 Raw data must be formatted for storage, processing,
and presentation
 Data are the foundation of information, which is the
bedrock of knowledge
54 Database Systems, 9th Edition

What is a Database?
 “A set of information held in a computer”
Oxford English Dictionary
 “One or more large structured sets of persistent data,
usually associated with software to update and query
the data”
Free On-Line Dictionary of Computing
 “A collection of data arranged for ease and speed of
search and retrieval”
Dictionary.com

Databases
 Web indexes
 Library catalogues
 Medical records
 Bank accounts
 Stock control
 Personnel systems
 Product catalogues
 Telephone directories
 Train timetables
 Airline bookings
 Credit card details
 Student records
 Customer histories
 Stock market prices
 Discussion boards
 and so on…

Database Systems
 A database system consists
of
 Data (the database)
 Software
 Hardware
 Users
 Database systems allow
users to
 Store
 Update
 Retrieve
 Organise
 Protect
their data.

Database Users
 End users
 Use the database system to
achieve some goal
 Application developers
 Write software to allow end
users to interface with the
database system
 Database Administrator
(DBA)
 Designs & manages the
database system
 Database systems
programmer
 Writes the database software
itself

Database Management Systems
 A database is a collection
of information
 A database management
system (DBMS) is the
software than controls that
information
 Examples:
 Oracle
 DB2 (IBM)
 MS SQL Server
 MS Access
 Ingres
 PostgreSQL
 MySQL

What the DBMS does
 Provides users with
 Data definition language
(DDL)
 Data manipulation language
(DML)
 Data control language (DCL)
 Often these are all the
same language
 DBMS provides
 Persistence – retains modification
 Concurrency – simultaneous access
 Integrity
 Security
 Data independence
 Data Dictionary
 Describes the database itself

Structural and Data Dependence
 Structural dependence: access to a file is dependent
on its own structure
 All file system programs must be modified to conform to
a new file structure
 Structural independence: change file structure
without affecting data access
 Data dependence: data access changes when data
storage characteristics change
 Data independence: data storage characteristics do
not affect data access

Structural and Data Dependence
(cont'd.) Practical significance of data dependence is
difference between logical and physical format
 Logical data format: how human views the data
 Physical data format: how computer must work
with data
 Each program must contain:
 Lines specifying opening of specific file type
 Record specification
 Field definitions

Data Redundancy File system structure makes it difficult to combine
data from multiple sources
 Vulnerable to security breaches
 Organizational structure promotes storage of same
data in different locations
 Islands of information
 Data stored in different locations is unlikely to be
updated consistently
 Data redundancy: same data stored unnecessarily in
different places
63

Data Redundancy (cont'd.)
 Data inconsistency: different and conflicting
versions of same data occur at different places
 Data anomalies: abnormalities when all changes in
redundant data are not made correctly
 Update anomalies
 Insertion anomalies
 Deletion anomalies

Types of Databases Databases can be classified according to:
 Number of users
 Database location(s)
 Expected type and extent of use
 Single-user database supports only one user at a
time
 Desktop database: single-user; runs on PC
 Multiuser database supports multiple users at the
same time
 Workgroup and enterprise databases

Types of Databases (cont’d.)
 Centralized database: data located at a single site
 Distributed database: data distributed across several
different sites
 Operational database: supports a company’s day-to-
day operations
 Transactional or production database
 Data warehouse: stores data used for tactical or
strategic decisions

Types of Databases (cont'd.)
 Unstructured data exist in their original state
 Structured data result from formatting
 Structure applied based on type of processing to be
performed
 Semistructured data have been processed to some
extent
 Extensible Markup Language (XML) represents
data elements in textual format
 XML database supports semistructured XML data

Introduction to mis

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