3. 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.
4. 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.
5. 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.
6. 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.
7. 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.
8. 4. Micro Computers These are the smallest range of
computers. They were introduced in the early 70s 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.
9. Input Devices Input Devices: devices that input information
into the computer such as a keyboard, mouse, scanner, and digital
camera.
10. Output Devices Output: devices that output information from
the computer such as a printer and monitor.
11. 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
12. 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.
13. 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
14. Data Storage Devices (contd) CD-ROM (compact disk read only
memory) Approximately 600 to 700 megabyte of storage An optical
device read by a diode laser
15. Data Storage Devices (contd) 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
16. 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
17. 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.
18. 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.
19. 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.
20. 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
21. Ports and Peripherals Peripherals are devices that plug
into a computer and are not housed internally. Examples: Printers
Scanners Cameras
22. 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.
23. 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
24. 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)
25. 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.
26. 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.
27. Multimedia Multimedia software programs include sound,
pictures, video, text, and hypertext to create presentations.
Software includes: PowerPoint Macromedia Director FLASH
28. 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
29. 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.
30. 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.
31. The End
32. 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.
33. Introduction to 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.
34. Introduction to Networks 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.
35. 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.
36. Need for Networks Enhance communication. Share resources.
Facilitate centralized management.
37. 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.
38. 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.
39. 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
40. 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.
41. 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.
42. 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.
43. Classification of Networks Classification by network
geography. Classification by component roles.
44. 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.
45. 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.
Classification by Network Geography
46. Local area network Classification by Network Geography
47. 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. Classification by Network
Geography
48. Metropolitan area network Classification by Network
Geography
49. 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. Classification by Network Geography
50. Wide area network Classification by Network Geography
51. Classification by Component Roles Networks can also be
classified according to the roles that the networked computers play
in the networks operation. Peer-to-peer, server-based, and
client-based are the types of roles into which networks are
classified.
52. 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
53. 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
54. 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
55. 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.
56. 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
57. 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
58. 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
59. 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 61 Database Systems, 9th
Edition
60. 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
61. 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
62. 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
63. 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 65 Database Systems, 9th Edition
64. Types of Databases (contd.) Centralized database: data
located at a single site Distributed database: data distributed
across several different sites Operational database: supports a
companys day-to- day operations Transactional or production
database Data warehouse: stores data used for tactical or strategic
decisions 66 Database Systems, 9th Edition
65. 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
