Categories and Classification of Computers

Categories of Computers
There are three major ways to categories Computers.
Size & Speed: By size and speed computers divided into 4 classification, depending upon the capacity and speed of processing the data
Working Principal: By working behaviors computers divided into 3 types, depending upon the data and how computers process the data
Technology: By technology computers divided into 5 generation, each generation has different hardware manufacturing technology.

Classification of Computers (By Size & speed)

Micro or Personal Computers



A personal computer (PC) is a computer that can perform all of its inputs, processing, outputs and storage activities by itself. A personal computer contains a processor, memory, and one or more input, output, and storage device.


Mini or Midrange Computers



It is larger and more powerful computers than personal computers. It can execute five billion instructions per second. It generally consists of two or more processors. It is more reliable than desktop computer. Mini computers were introduced in 1960s. Mini computers are used in small companies to provide centralized store of information.

Mainframe Computers



A mainframe is a large computer in term of price, power and speed. It consists of multiple processors. It is specially designed to perform multiple intensive tasks for multiple users simultaneously. It was introduced in 1970s. A typical mainframe computer can execute 16 million instructions per second.
It is used in large organizations, such as banks, Universities and Multinational companies etc.

Super Computers



Super computer is the biggest in size, most expensive in price and powerful than any other computer. It can process trillions of instructions in one second. The modern super computer consists of thousands of microprocessors.
Super computers are used in weather forecasting, weapon design, preparing models of chemical and biological system, mapping the surface of the planets and studying the neural network of the brain.

Generation of Computer

Generation of Computer
Generation” in computer talk is a new step in hardware or software technology.
Different generations of computer are as follows:



Generation



Technology



Description



1st Generation
(1942-1955)




Vacuum Taube



Vacuum tubes (fragile glass device) were the only electronic component available during those days that possible to make electronic digital computer.
These computers can calculate data in millisecond; these were very large in size.
Examples: UNIAC, EDVAC, EDSAC



2nd Generation
(1956-1964)




Transistor



The transistor (Solid State Device) a smaller and more reliable successor to the vacuum tube was invented in 1947
Faster in speed from the previous computers. These computers were able to reduce computational time from milliseconds to microseconds.
Examples: UNIVAC III, SS80, SS90, 1107



3rd Generation
(1964-1975)




Integrated Circuits



Advance “Microelectronic” technology made it possible to integrate larger number of circuit elements into very small (less than 5 mm square) surface of silicon know as Chip or Integrated Circuit(IC). The use of IC in place of transistors gave birth of new generation. they were able to reduce computational time from microseconds to nanoseconds Examples: IBM System/360 Series



4th Generation
(1975-Present)



VLSI



Small Scale Integration (SSI) contains ten to twenty ICs components. Medium Scale Integration (MSI), which has hundreds of integrated components in a single chip. Large Scale Integration (LSI) possible to integrate 30,000 components into a single chip. Very Large Scale Integration (VLSI) contains one million components integrated on a single chip.

Photoshop Tool box Overview

Photoshop Tool box Overview
The toolbox contains the main tools for working on images. Click any tool to select and use it.
A small arrow next to a tool in the toolbox indicates that the tool also has additional options available. In Photoshop, click and hold your mouse on a tool to see its options. For example, if you click and hold on the select tool, you'll see select options such as eliptical selction, single row selection, etc.

    

Network basic terms

DATA COMMUNICATION AND NETWORK
Terms
Communication
Communication means to an exchange of information between two or more parties and it can be exchange in a Varity of way.
Data or computer Communication is the transmission of data and information over a communications channel between two computers which can be several different things
Channel, in communications (sometimes called communications channel), refers to the medium used to convey information from a sender (or transmitter) to a receiver.
Transmission Media
It is necessary to have a pathway or the media to be transmitted data from one point to another. The term media means the device that transmits the voice or the data form one point to another.
Guided Media
In Guided media the messages flow through the physical media like twisted pair-wire, coaxial cable fiber optic cables, the media guided is the signal.
Coaxial Cabling

Coaxial cable has a copper core (inner conductor) with an outer cylindrical shell for insulation. it is more expensive and difficult to work with and relatively inflexible and also it cost 10-20 times more then twisted pair.

Twisted Pair Cables

 Twisted- pair wire is the most commonly used wire.  There are two types of twisted pair cable, shielded and unshielded twisted pair. Shielded twisted pair (STP) cable consists of pairs of insulated solid wire surrounded by a braided or corrugated shielding. 

 Another type of twisted pair is Unshielded twisted pair (UTP) which is most frequently used network cabling because of It is relatively inexpensive to purchase.

Unshielded twisted pair is telephone wire consisting of wire pairs within an insulated outside covering.

Type	Use
Category 1	Voice Only (Telephone wire)
Category 2	Data to 4 Mbps (LocalTalk)
Category 3	Data to 10 Mbps (Ethernet)
Category 4	Data to 20 Mbps (16 Mbps Token Ring)
Category 5	Data to 100 Mbps (Fast Ethernet)
Category 6	Data to 1000 Mbps (Fast Ethernet)
Category 7	Data to 10 Gbps (Fast Ethernet)

Fiber Optic

Fiber optics consists of thousands of very thin filaments of glass fibers which can conduct lights pulse generated by laser at transmission frequencies that approach the speed of lights. Fiber optics has greater data transmission rate as well as the great security interference tapping.  

UnGuided (Radiated) Media:- in unguided media messages is broadcast through the air such as infrared, microwave, or satellite

Infra-Red
There are many systems today using infra-red communications. This is usually a directional infrared light signal transmitted into the air and received by nearby devices.
Radio and Microwave
These are the signals we think of as being radio, television and satellite, but they are now being put to use in wireless Ethernet and Bluetooth communications technologies.

 

Satellites
The satellite contains a transponder consisting of a radio receiver and transmitter. A ground station on one side of the ocean sends a signal to the satellite, which amplifies it and transmits the amplified signal at a different angle than it arrived at to another ground station on the other side of the ocean.
Signals
Computer uses two types of signals for data transmission are used Analog and Digital.
Digital Signals
A digital signal is a stream of “0” and “1” so this type of signals is appropriate particularly for today computer.
Analog Signals
Analog signals uses variation in a signals to convey information. It is particularly useful for Wave data like sound waves. Our phone lines and speakers are the Examples of Analog Signals.
Modem
Modem word derived from Modulation and Demodulation. A modem is a device that modulates and demodulates the signals. Modulation means conversion of Digital Signals into Analog signals While Demodulation means conversion of Analog signals into Digital signals. Modems are always use in pairs. It is used to connect to the Internet or Global Network.






Network
Te interconnection of more than two computes so that they can share data & resources like printer, CD-ROM is called as a Network.
A Simple Computer Network for File Sharing


                       

 

 

 

 

Network classification
Networks are classified according to their geographical coverage and size. The two most common network classifications are local area networks (LANs) and wide area networks (WANs).
LANs (Local Area Network)
A Local Area Network (LAN) is a network that is confined to a relatively small area. It is generally limited to a geographic area such as a writing lab, school, or building. On most LANs, cables are used to connect the network interface cards (NIC) in each computer.

 

WANs (Wide Area Network)

Wide Area Networks (WANs) connect larger geographic areas, Using a WAN, schools in Multan can communicate with places like Karachi in a matter of minutes, without paying enormous phone bills.

Microsoft Excel 2007

Microsoft Excel 2007

Spreadsheet
The word "spreadsheet" came from "spread" in its sense of a newspaper or magazine item (text and/or graphics) that covers two facing pages, extending across the center fold and treating the two pages as one large one. The compound word "spread-sheet" came to mean the format used to present book-keeping ledgers—with columns for categories of expenditures across the top, invoices listed down the left margin, and the amount of each payment in the cell where its row and column intersect—which were, traditionally, a "spread" across facing pages of a bound ledger (book for keeping accounting records) or on oversized sheets of paper ruled into rows and columns in that format and approximately twice as wide as ordinary paper.
A spreadsheet is a computer application that simulates a paper, accounting worksheet. It displays multiple cells that together make up a grid consisting of rows and columns.
Introduction
Microsoft Excel is an excellent program for organizing, formatting, and calculating numeric data. Excel displays data in a row-and-column format, with gridlines between the rows and columns, similar to accounting ledger books or graph paper. Consequently, Excel is well suited for working with numeric data for accounting, scientific research, statistical recording, and any other situation that can benefit from organizing data in a table- format. e.g. Teachers often record student grade information in Excel..
Excel run by using any of three methods that use to run Microsoft Word.
When you start Excel, a blank workbook, titled Book1, opens by default.
Worksheets
Microsoft Excel consists of worksheets. Each worksheet contains columns and rows. The columns are lettered A to Z and then continuing with AA, AB, AC and so on; the rows are numbered 1 to 1,048,576. The number of columns and rows you can have in a worksheet is limited by your computer memory and your system resources.
The combination of a column coordinate and a row coordinate make up a cell address. For example, the cell located in the upper-left corner of the worksheet is cell A1, meaning column A, row 1. Cell E10 is located under column E on row 10. You enter your data into the cells on the worksheet.

Microsoftw Word 2007

Microsoft Word 2007
Word Processor
Word Processor is software that helps you to create any type of written communication like a letter, a report, a memo, or any other type of correspondence or text data.                  
(i.e. Microsoft Word, Word Pad ,Word Star and Word Perfect are the common word processors). But the Microsoft Word is popular word processor.

MS Word 2007
Microsoft Word is part of the Microsoft Office. Its main function is for producing documents that can includes text, graphics, table, clip art, etc. The most familiar application among the members of the Office is Word.
This lesson will introduce you to the Word window, open Microsoft Word 2007. The Microsoft Word window appears and screen looks similar to the one shown here.
Understanding Document Views
In Word 2007, you can display your document in one of five views: Draft, Web Layout, Print Layout, Full Screen Reading, or Online Layout.
Draft View
Draft view is the most frequently used view. You use Draft view to quickly edit your document.
Web Layout
Web Layout view enables you to see your document as it would appear in a browser such as Internet Explorer.
Print Layout
The Print Layout view shows the document as it will look when it is printed.
Reading Layout
Reading Layout view formats your screen to make reading your document more comfortable.
Outline View
Outline view displays the document in outline form. You can display headings without the text. If you move a heading, the accompanying text moves with it.

INTRODUCTION TO COMPUTER SYSTEM

INTRODUCTION TO COMPUTER SYSTEM
The word “Computer” has been derived from the Latin word “Compute” which means to Calculate

A computer is an programmable electronic device that can accept data, perform arithmetic (+,-,x,/) & logical (<,>,=,≠) operation on the data, produce the required results.
Normally, a computer is considered to be a calculating device that can perform arithmetic and logical operations at a great speed.



Components of Computer
Basically, a computer consists of four components

Hardware: The physical or tangible parts of the computer called hardware. Like Monitor, Keyboard, CPU, Mouse etc.

Software: The set of instructions, that tells the computer, what to do and how to do.

Data: A collection of raw facts and figures is called data, which can include text, numbers, images, audios and videos etc.

User: Computer cannot do any without its operator.



Information
The processed form of data is called information. Information conveys meaning and is useful to one or more people..

Information Processing Cycle (IPC)
Information processing cycle consists of a series of tasks or steps required to convert data into information. Different steps of information processing cycle are as follows.


Characteristics of Computers.
Computers are powerful for a verity of reasons. They operate with amazing speed reliability, consistency, and accuracy. Computer can store huge amount of data and information.

Speed: Most computers carry out billions of operations in a single second. The words fastest computer can perform trillions of operations in one second.
Reliability and consistency: The electronic components in modern computers are dependable because they have a low failure rate. The high reliability of computer enables to computer to produce consistence results. So it correct & tireless machine.
Storage: Computer is used due to its large storage capacity. A data that you can place in 100 (7x4) feet almirah can be stored in a computer on a 2 x 2 inch area.
Adoptability: computer has ability to work with and to control each & every electronic device. To plug camera, motors, fax, and many other machines with it to get required results.