Basic TCP IP TCP and UDP Communication

COMPUTER HARDWARE

A computer has electronic and mechanical parts known as hardware. That is, the physical components that make up a computer system is known as computer hardware. Hardware includes input devices, output devices, system unit, storage devices and communication devices. Without these components we would not be able to use the computer.

Input Devices:
An input device is any hardware component that allows you the user to enter data into the computer. There are many input devices. Some most widely used input devices are:

• A keyboard: You use the keyboard to type letters, numbers and symbols into the computer.
  
• A Mouse: The mouse is a pointing device that has a pointer that changes into different shapes as you use the mouse. You click the mouse by pressing and releasing the button. This action allows you to enter data when using a mouse.
  
• A Scanner: This input device copies from paper into your computer.
  
• A Microphone: The microphone is usually used for voice input into the computer.
  
• A Digital Camera: The digital camera allows you to take pictures that you can input into your computer.
  
• A PC Video Camera/Web Camera: The PC video camera allows you take both video and still images that you can input onto your computer.
  

Output Devices:
An output device is any hardware component that gives information to the user. Three commonly used output devices are:

1. A Monitor: This output device displays your information on a screen.
2. A Printer: This output device prints information on paper. This type of printed output is called a hard copy.
3. A Speaker: Sound is the type of output you will get from a speaker. 

The System Unit:

See the picture, it is the case that contains all the electronic components of any computer system, it is called the System Unit or Central Processing Unit of a computer. The electronic components are considered internal hardware seeing that they are inside the system unit and you cannot see when you look at the computer. These components inside the system unit are what process the data and really make the computer work. Internal components are as follows:

• Power Supply: The power supply converts electricity into the current works for the computer. When the computer is turned on the power supply allows converted electricity to travel to other components inside the computer.
• Motherboard: The motherboard is the circuit board that holds the main internal components of the computer together. On the motherboard there are three major cards; sound card that operates the sound, the video card that handles the graphics that you see on the monitor and the modem card which allows computers to communicate with each other. Also on the motherboard is the Central Processing Unit (CPU), processor or brain of the computer. The CPU controls information and tells the other components inside the computer what to do.
• RAM & ROM: RAM stands for Random Access Memory. This memory holds the information you are working with while the computer is turned on. Once you turn the computer off all the information that was in RAM will be gone. ROM stands for Read Only Memory. This memory holds information that you can only read, but not erase. Information in ROM is built in and is always there even when the computer is turned off.
• Disk Drives: The disk drive is the device that reads information that is on disk. Generally speaking most computers have three disk drives; Hard Disk Drive, Floppy Disk Drive and CD-ROM Drive. However, the Floppy Disk Drives are not used nowadays but have DVD-ROM Drives. While the hard disk is hidden inside the computer the Floppy, DVD-ROM and CD-ROM drives are accessible from the front of the system unit.

The hardware parts are labeled in the diagram.

1. Monitor

2. Motherboard

3. CPU

4. RAM

5. Expansion Cards / Graphics Card / Sound Card / Network Card

6. Power Supply

7. Optical Disc Drive

8. Hard Disk Drive

9. Keyboard

10. Mouse

COMPUTER SOFTWARE

The computer will not work without software. Software also call programs are the instructions that tell the computer what to do and how o do it. The two main categories of software are system software and application software.

The system software also called the operating system (OS) actually runs the computer. This software controls all the operations of the computer and its devices. All computers use system software and without the system software the application software will not work. The most common OS on a PC is the Windows operating system and for the Mac computer it would be the Mac operating system.

Application software is a program that allows users to a specific task on the computer. There are a number of different types of application software available to do many of the tasks we do daily. Four examples of common application software and what they are used for are:

• Word Processing Application: One word processing program is Microsoft Word. This program allows you to type letters, assignments and do any other written activity on the computer.
• Spreadsheet Application: Microsoft Excel is an example of a spreadsheet program. One can use this program to create charts and do calculations.
• E-mail Application: Outlook Express is an e-mail program that allows you to receive and send e-mails.
• Internet Application: Internet Explorer is a program that allows you to get connected to the Internet and look at Web sites like the one you are reading now.

The third category of computer software is malicious software or malware, computer software developed to harm and disrupt computers. Malware is closely associated with computer-related crimes.

COMPUTER - Questions & Answers

Q1.What is a computer?

       A. A computer is an electronic machine operating under the control of instructions.

Q2.How many generations of computers are there? 

       A. There are three generations of computers.

Q3.What are the categories of computers? 

       A. The categories of computer are supercomputer, mainframe computer and personal computer.

Q4.What is software? 

       A. Software is the program or instructions that make the computer work.

Q5.What is hardware? 

       A. Hardware is the physical and electronic component of the computer system.

Q6.What are storage media? 

       A. Storage media are the physical materials that user stores data, information and instructions on for future use.

Q7.What does the acronym CPU stands for? 

       A. CPU - Central Processing Unit.

Q8.What do the acronyms ROM and RAM stand for? 

       A. ROM – Read Only Memory & RAM – Random Access Memory.

Q9.What is the difference between input and output? 

       A. Input is what is entered into the computer, while output what you seen on the monitor or what is printed out.

Q10. What is the difference between data and information? 

       A. Data is what is entered into to the computer to be processed, while information is processed data.

TYPES OF COMPUTERS

There are three different types of computers according to the principles of operation.

1. Analog Computers: Analog Computer is a computing device that works on continuous range of values. The results given by the analog computers will only be approximate since they deal with quantities that vary continuously. It generally deals with physical variables such as voltage, pressure, temperature, speed, etc.

2. Digital Computers: On the other hand a digital computer operates on digital data such as numbers. It uses binary number system in which there are only two digits 0 and 1. Each one is called a bit. The digital computer is designed using digital circuits in which there are two levels for an input or output signal. These two levels are known as logic 0 and logic 1. Digital Computers can give more accurate and faster results. Digital computer is well suited for solving complex problems in engineering and technology. Hence digital computers have an increasing use in the field of design, research and data processing.

Based on the purpose, Digital computers can be further classified as:

· General Purpose Computers

· Special Purpose Computers

Special purpose computer is one that is built for a specific application. General-purpose computers are used for any type of applications. They can store different programs and do the jobs as per the instructions specified on those programs. Most of the computers that we see today are general-purpose computers.

3. Hybrid Computers: A hybrid computer combines the desirable features of analog and digital computers. It is mostly used for automatic operations of complicated physical processes and machines. Now-a-days analog-to-digital and digital-to-analog converters are used for transforming the data into suitable form for either type of computation. For example, in hospital’s ICU, analog devices might measure the patients’ temperature, blood pressure and other vital signs. These measurements, which are in analog, might then be converted into numbers and supplied to digital components in the system. These components are used to monitor the patient’s vital sign and send signals if any abnormal readings are detected. Hybrid computers are mainly used for specialised tasks.

There are four different types of computers based on their performance and capacity.

1. Super Computers: When we talk about types of computers, the first type that comes to our mind would be Super Computers. They are the best in terms of processing capacity and also the most expensive ones. These computers can process billions of instructions per second. Normally, they will be used for applications, which require intensive numerical computations such as stock analysis, weather forecasting etc. Other uses of supercomputers are scientific simulations, (animated) graphics, fluid dynamic calculations, nuclear energy research, electronic design, and analysis of geological data (e.g. in petrochemical prospecting).

2. Mainframe Computers: Mainframe computers can also process data at very high speeds, that is, hundreds of million instructions per second and they are also quite expensive. Normally, they are used in banking, airlines and railways etc. for their applications.

3. Mini Computers: Mini computers are lower to mainframe computers in terms of speed and storage capacity. They are also less expensive than mainframe computers. Some of the features of mainframes will not be available in mini computers. Hence, their performance also will be less than that of mainframes.

4. Micro Computers: The invention of microprocessor (single chip CPU) gave birth to the much cheaper microcomputers. They are further classified into

· Desktop Computers

· Laptop Computers

· Handheld Computers (PDAs)

Desktop Computers: Today the Desktop computers are the most popular computer systems. These desktop computers are also known as personal computers or simply PCs. They are usually easier to use and more affordable. They are normally intended for individual users for their word processing and other small application requirements.

Laptop Computers: Laptop computers are portable computers. They are lightweight computers with a thin screen. They are also called as notebook computers because of their small size. They can operate on batteries and hence are very popular with travellers. The screen folds down onto the keyboard when not in use.

Handheld Computers: Handheld computers or Personal Digital Assistants (PDAs) are pen-based and also battery-powered. They are small and can be carried anywhere. They use a pen like stylus and accept handwritten input directly on the screen. They are not as powerful as desktops or laptops but they are used for scheduling appointments, storing addresses and playing games. They have touch screens that we use with a finger or a stylus.

COMPUTER - A BRIEF HISTORY

A computer is a general-purpose device that can be programmed to carry out a set of arithmetic or logical operations. Charles Babbage, a mathematician, philosopher, inventor and mechanical engineer, who is considered as "Father of the Computer", designed the Analytical Engine and it was the basic frameworks of the computers of today are based on.

GENERATIONS OF COMPUTERS:

Generally computer generations can be classified in to three. 

1. First Generation: 1937 – 1946:- In 1937 the first electronic digital computer was built by Dr. John V. Atanasoff and Clifford Berry. It was called the Atanasoff-Berry Computer (ABC). In 1943 an electronic computer name the Colossus was built for the military. Other developments continued until in 1946 the first general– purpose digital computer, the Electronic Numerical Integrator and Computer (ENIAC) was built. It is said that this computer weighed 30 tons, and had 18,000 vacuum tubes, which was used for processing. When this computer was turned on for the first time lights dim in sections of Philadelphia. Computers of this generation could only perform single task, and they had no operating system.

2. Second Generation: 1947 – 1962:- This generation of computers used transistors instead of vacuum tubes which were more reliable. In 1951 the first computer for commercial use was introduced to the public; the Universal Automatic Computer (UNIVAC 1). In 1953 the International Business Machine (IBM) 650 and 700 series computers made their mark in the computer world. During this generation of computers over 100 computer programming languages were developed, computers had memory and operating systems. Storage media such as tape and disk were in use also were printers for output.

3. Third Generation: 1963 - Present:- The invention of integrated circuit brought us the third generation of computers. With this invention computers became smaller, more powerful more reliable and they are able to run many different programs at the same time. In1980 Microsoft Disk Operating System (MS-Dos) was born and in 1981 IBM introduced the personal computer (PC) for home and office use. Three years later Apple gave us the Macintosh computer with its icon driven interface and the 90s gave us Windows operating system.