Introduction to Computer Basic

Computer

A computer is an electronic device, operating under the control of instructions stored in its memory that can accept data (input), process the data according to specified rules, produce information (output), and store the information for future use.

To put it simply, a computer is an electronic device that is designed to work with information.

The Computer…

• 1. Takes in the INPUT information, then.
• 2. PROCESS the information, and then.
• 3. Displays the OUTPUT results.

Functionalities of a computer

Any digital computer carries out five functions in gross terms:

• Takes data as input
• Stores the data/instructions in its memory and uses them when required.
• processes the data and converts it into useful information.
• Generates the output.
• controls all the above four steps.

Computer Components

Any kind of computer consists of HARDWARE AND SOFTWARE

Hardware: Computer hardware is the collection of physical elements that constitute a computer system. Computer hardware refers to the physical parts or components of a computer such as a monitor, mouse, keyboard, computer data storage, hard drive disk (HDD), system unit (graphic cards, sound cards, memory, motherboard, and chips), etc. all of which are physical objects that can be touched.

1. INPUT DEVICES:- An input device is any peripheral (a piece of computer hardware equipment to provide data and control signals to an information processing system such as a computer or other information appliance.
   
   Input device Translate data from a form that humans understand to one that the computer can work with. The most common are keyboard and mouse.
   

Example of Input Devices:-

1. Keyboard	2. Touch screen	3.Microphone
4.Touch screen	5. Mouse (pointing device)	6. Webcam
7. Touchpads	8. MIDI Keyboard	9. Graphics Tablets
10. Cameras	11. Pen Input	12. Video capture Hardware
13. Microphone	14. Trackballs	15. Barcode
16. Digital Camera	17. Joysticks	18. Gamepad
19. Electronic whitepad	20. Remote control	19. Light pens

Note: The most commonly used keyboard is the QWERTY keyboard. Generally, a standard Keyboard has 104 keys.

2. Central Processing Unit (CPU):- A CPU is the brain of a computer. It is responsible for all functions and processes. Regarding computing power, the CPU is the most important element of a computer system.

The CPU is comprised of three main parts :

• Arithmetic Logic Unit (ALU): Executes all arithmetic and logical operations. Arithmetic calculations like addition, subtraction, multiplication, and division. Logical operations like comparing numbers, letters, or special characters
• Registers: Stores the data that is to be executed next, “very fast storage area”.
• Control Unit (CU): controls and coordinates computer components.

1. Read the code for the next instruction to be executed.
2. Increment the program counter so it points to the next instruction.
3. Read whatever data the instruction requires from cells in memory.
4. Provide the necessary data to an ALU or register.
5. If the instruction requires an ALU or specialized hardware to complete, instruct the hardware to perform the requested operation.

3. Primary Memory:-

• RAM: Random Access Memory (RAM) is a memory scheme within the computer system responsible for storing data temporarily so that it can be promptly accessed by the processor as and when needed. It is volatile, which means that data will be erased once the supply to the storage device is turned off. RAM stores data randomly and the processor accesses these data randomly from the RAM storage. RAM is considered “random access” because you can access any memory cell directly if you know the row and column that intersect at that cell.
• ROM (Read Only Memory): ROM is a permanent form of storage. ROM stays active regardless of whether the power supply to it is turned on or off. ROM devices do not allow data stored on them to be modified

4. Secondary Memory:– Stores data and programs permanently. It is retained after the power is turned off

• Hard drive (HD): A hard disk is part of a unit, often called a “disk drive,” “hard drive,” or “hard disk drive,” that stores and provides relatively quick access to large amounts of data on an electromagnetically charged surface or set of surfaces.
• Optical Disk: an optical disc drive (ODD) is a disk drive that uses laser light as part of the process of reading or writing data to or from optical discs. Some drives can only read from discs, but recent drives are commonly both readers and recorders, also called burners or writers. Compact discs, DVDs, and Blu-ray discs are common types of optical media that can be read and recorded by such drives. An optical drive is a generic name; drives are usually described as “CD” “DVD”, or “Bluray”, followed by “drive”, “writer”, etc. There are three main types of optical media: CD, DVD, and Blu-ray discs. CDs can store up to 700 megabytes (MB) of data and DVDs can store up to 8.4 GB of data. Blu-ray discs, which are the newest type of optical media, can store up to 50 GB of data. This storage capacity is a clear advantage over the floppy disk storage media (magnetic media), which only has a capacity of 1.44 MB.
• Flash Disk:- A storage module made of flash memory chips. Flash disks have no mechanical platters or access arms, but the term “disk” is used because the data are accessed as if they were on a hard drive. The disk storage structure is emulated.

Comparison between main memory(RAM) and Secondary Memory(Hard disk)

RAM	Hard Disk(Hard Drive)
It is a Volatile Memory that stores information or data temporarily for easy and instant access.	It is a non-volatile memory that is the main data storage hardware device in a computer.
Smaller amount (typically 500MB-6GB)	Much larger amount (typically 80GB to 100 GB)
Temporary storage of files and programs	Permanent storage of files and programs
RAM affects the speed of the computer.	Hard disk does not affect the computer.
RAM is smaller than HDDs	HDDs are usually larger than RAM
RAM has shorter read and write time.	HDDs have longer read and write time.
It consists of chips (Microprocessors)	It consists of hard disks (platters)

5. Output Devices:- An output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by an information processing system (such as a computer) which converts the electronically generated information into human-readable form.

Note Basic types of monitors are
a.Cathode Ray Tube (CRT).
b. Liquid Crystal Displays (LCD).
c.light-emitting diode (LED).

Printer types:
1-Laser Printer.
2-Ink Jet Printer.
3-Dot Matrix Printer

Software

Software is a generic term for organized collections of computer data and instructions, often broken into two major categories: system software which provides the basic nontask-specific functions of the computer, and application software which is used by users to accomplish specific tasks.

• Software Types
• System software:- It is responsible for controlling, integrating, and managing the individual hardware components of a computer system so that other software and the users of the system see it as a functional unit without having to be concerned with the low-level details such as transferring data from memory to disk, or rendering text onto a display. Generally, system software consists of an operating system and some fundamental utilities such as disk formatters, file managers, display managers, text editors, user authentication (login) and management tools, and networking and device control software.
  
• Application software:- It is used to accomplish specific tasks other than just running the computer system. Application software may consist of a single program, such as an image viewer; a small collection of programs (often called a software package) that work closely together to accomplish a task, such as a spreadsheet or text processing system; a larger collection (often called a software suite) of related but independent programs and packages that have a common user interface or shared data format, such as Microsoft Office, which consists of a closely integrated word processor, spreadsheet, database, etc.; or a software system, such as a database management system, which is a collection of fundamental programs that may provide some service to a variety of other independent applications.

Comparison of Application Software and system software

	System Software	Application Software
	Computer software, or just software is a general term primarily used for digitally stored data such as computer programs and other kinds of information read and written by computers. App comes under computer software though it has a wide scope now.	Application software, also known as an application or an “app”, is computer software designed to help the user to perform specific tasks.
Example:	1) Microsoft Windows 2) Linux 3) Unix 4) Mac OSX 5) DOS	1) Opera (Web Browser) 2) Microsoft Word (Word Processing) 3) Microsoft Excel (Spreadsheet software) 4) MySQL (Database Software) 5) Microsoft PowerPoint (Presentation Software) 6) Adobe Photoshop (Graphics Software)
Interaction:	Generally, users do not interact with system software as it works in the background	Users always interact with application software while doing different activities.
Dependency:	System software can run independently of the application software.	Application software cannot run without the presence of the system software

Unit of Measurements

Storage measurements: The basic unit used in computer data storage is called a bit (binary digit). Computers use these little bits, which are composed of ones and zeros, to do things and talk to other computers. All your files, for instance, are kept in the computer as binary files and translated into words and pictures by the software (which is also ones and zeros). This two-number system is called a “binary number system” since it has only two numbers in it. The decimal number system in contrast has ten unique digits, zero through nine.

Bit	BIT	0 or 1
Kilobyte	KB	1024bytes
Megabyte	MB	1024kilobytes
GigaByte	GB	1024 megabytes
Tera Byte	TB	1024 gigabytes

Size example

• 1 bit – answer to a yes/no question
• 1 byte – a number from 0 to 255.
• 90 bytes: enough to store a typical line of text from a book.
• 4 KB: about one page of text.
• 120 KB: the text of a typical pocketbook.
• 3 MB – a three-minute song (128k bitrate)
• 650-900 MB – a CD-ROM
• 1 GB -114 minutes of uncompressed CD-quality audio at 1.4 Mbit/s
• 8-16 GB – the size of a normal flash drive

Speed measurement: The speed of the Central Processing Unit (CPU) is measured by Hertz (Hz), Which represents a CPU cycle. The speed of the CPU is known as the Computer Speed.

Types of computers

Computers can be generally classified by size and power as follows, through their considerable overlap.

Based on size:-

1. Mainframe:- A powerful multi-user computer capable of supporting many hundreds or thousands of users simultaneously. Mainframe computers can also process data at very high speeds i.e., hundreds of million instructions per second and they are also quite expensive. Normally, they are used in banking, airlines railways, etc. for their applications.
   
   Characteristics of Mainframe:-

• It is light weight making it easy to carry and fit anywhere.
• It has high storage capacity and great performance
• It is less expensive than mainframe computers.
• It runs smoothly for a long time and has a long life.

2. 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 mainframe computers.

Characteristics of Mini Computers

• Its weight is low due to weight low its carry anywhere.
• less expensive than a mainframe computer.
• It is fast.

3. Supercomputer:- When we talk about types of computers, the first type that comes to our mind would be Supercomputers. 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.

Characteristics of supercomputer

• Supercomputers are the computers that are the fastest and they are also very expensive.
• It is also used in a smog control system where it predicts the level of fog and other pollutants in the atmosphere
• It has played a vital role in managing the online currency world such as the stock market and the bitcoin
• It is used for virtual testing of nuclear weapons and critical medical tests.
• It is used in scientific research areas for analyzing data obtained from exploring the solar system, satellites, etc.

4. Workstation:- A workstation is a single user design computer for technical or scientific applications. It has a faster microprocessor, a large amount of RAM and high speed graphic adapters. It is a single-user computer. It is generally used to perform a specific task with great accuracy.

Characteristics of Workstation computer

• It is expensive or high in cost.
• They are exclusively made for complex work purposes.
• It has larger storage capacity, better graphics, and more powerful CPU than a personal computer

5. MICRO COMPUTERS:- Microcomputer is at the lowest end of the computer range in terms of speed and storage capacity. Its CPU is a microprocessor. The first microcomputers were built of 8-bit microprocessor chips. The most common microcomputer is a personal computer (PC). The PC supports a number of input and output devices. An improvement of 8-bit chip is 16-bit and 32-bit chips. Examples of microcomputer are IBM PC, PC-AT.

Characteristics of Micro computer

• It is less expansive and easy to use.
• It does not require the user to have special skills or training to use it.
• In this limited number of software can be used.
• It is designed for personal work and applications. Only one user can work at a time.
• Generally, comes with single semiconductor chip.

Based on Electronic signal they transmit:-

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:- 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. Based on the purpose, Digital computers can be further classified as:
   
   a. General Purpose Computers
   b. Special 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

CHARACTERISTICS OF A COMPUTER

The major characteristics of a computer are:-

1. Speed:-
   
   As you know computer can work very fast. It takes only few seconds for calculations that we take hours to complete. You will be surprised to know that computer can perform several million (1,000,000) of instructions and even more per second. Therefore, we determine the speed of computer in terms of microsecond (10^-6 part of a second) or nano-second (10^9 part of a second). From this you can
   imagine how fast your computer can perform.
   
2. Accuracy:-
   
   Suppose someone calculates faster but commits a lot of errors in computing, then such a result is useless. There is another aspect, suppose you want to divide 15 by 7. You may work out up to 2 decimal places and say the quotient is 2.14. I may calculate up to 4 decimal places and say that the result is 2.1428. Someone else may go up to 9 decimal places and say the result is 2.142857143.
   
   But a computer can give up to 100 decimal places within a fraction of second and that too accurately. Hence, in addition to speed, the computer provides very high level of accuracy or correctness in computing.
   
3. Diligence:-
   
   A computer is free from tiredness, lack of concentration, fatigue, etc. It can work for hours or days together very attentively without creating any error. If millions of calculations are to be performed, a computer will perform every calculation with the same accuracy. Due to this capability it is better than human being in routine and repetitive types of work.
   
4. Versatility:-
   
   It means the capacity to perform completely different type of work. You may use your computer to prepare payroll slips. Next moment you may use it for inventory management or to prepare electricity bills or prepare accounts, etc. Therefore computer is highly versatile.
   
5. Multi-tasking:-
   
   A human being cannot do more than one task at the same time without losing his concentration or with his full efficiency. But for a computer, it is a normal thing to do many tasks simultaneously without compromising in its efficiency. For example, at the same time you may use the computer to type a letter and to listen to your favourite music and also you can open internet web pages to get some information. This is known as Multi-tasking.
   
   
6. Power of Memory or Storage:-
   
   Computer has the power of storing huge amount of information or data. Information can be stored and recalled as long as you require it, for any number of years. It depends entirely upon you, how much data you want to store in a computer and when to use or retrieve these data. It will not fade away like human memory as years pass. The computer has an in-built memory where it can store a large amount of data. You can also store data in secondary storage devices such as floppies and CDs, which can be kept outside your computer and can be carried to other computers.
   
7. Reliability
   
   A computer is reliable. The output results never differ unless the input varies. the output is totally depend on the input. when an input is the same the output will also be the same. A computer produces consistent results for similar sets of data, if we provide the same set of input at any time we will get the same result.
   
   
8. No IQ
   
   Believe me! Computer is a dumb machine and it cannot do any work without instructions from the user. It is considered as a faithful idiot that can only perform the instructions given to it at a tremendous speed and with high accuracy without understanding of the work being done by it. Computer has to be guided as to what you want to do and in what sequence. So a computer cannot take its own decision as you can. So we humans are great!!!
   
   
9. No Feelings:-
   Computers do not have feelings or emotion, taste, knowledge and experience. Thus a computer does not get tired even after doing long hours of work. It does not distinguish between users and different kinds of work being done by it.