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starting with computer class -1 day

Set (Parts) of the Computer:
1. Power Supply, Electricity [Volt Guard, Stabilizer, UPS (Uninterruptible Power Supply)]
2. Input Device
- Mouse
- Keyboard
3. CPU (Central Processing Unit)
- Arithmetic and Logic Unit (ALU)
- Control Unit (CU)
4. Output Device
- Monitor (Screen)
- Printer (Impact, Dot Matrix Printer & Non-impact, Laser/Inkjet)
5. Memory Device (Attach to the CPU)
The main purpose of the memory is to store programs and data so that the CPU may access and process it. It also can store partial solutions during the computer run.
There are main two types of memory:
a) Primary Memory
i) RAM (Random Access Memory or Read Write Memory)
ii) ROM (Read only Memory)
The processor of a system retrieves data and instructions from the primary memory in order to execute program with the help of CU and ALU.
b) Secondary Memory
i) Flexible or Floppy Disks (A: or B:)
ii) Solid or Hard Disk (C: or D:)
iii) Compact Disk- CD (E: or F:)
Characteristics of Computer:
Speed and Accuracy Capabilities
Computer performs complex calculation at a very high speed. Computer takes a few micro/nano second to execute an operation.
Fractions of a Second:
1 Millisecond (m) = 1/1000 Thousandth of a Second (10-3) = 1/103
1 Microsecond (ยต) = 1/1000000 Millionths of a Second (10-6) = 1/106
1 Nanosecond (n) = 1/1000000000 Billionth of a Second (10-9) = 1/109
1 Pico Second (p) = 1/1000000000000 Trillionth of a Second (10-12) = 1/1012
1 Femtosecond (f) = 1/1000000000000000 Quadrillion of a second (10-15) = 1/1015
Computer always gives 100% actual output (result), If the user provides correct input and instruction. If any mistake occurs in any calculation they are due to manual error not of computer. Since it is produces highly accurate, reliable result.
Storage Capability:
The computers have the ability to store a huge amount of data in its secondary devices like floppy and hard disk. The storing capacity of computer is expressed in Bytes. Normally one byte stores one character of data.
0, 1 = 1 Bit ( Represent single bit either 1 or 0 or ON or OFF)
4 Bits or ½ byte = 1 Nibble = Group of 4 bit
8 Bits (2 Nibble) = 1 Byte
1 Byte = 1 Character
2 byte or 16 bits = 1 word
2 words or 32 bits = Double word
1024 Bytes (1000) = 1 KB (Kilo Byte) = 210 or 103
1024 KBs (1000) = 1 MB (Mega Byte) = 220 or 106
1024 MBs (1000) = 1 GB (Giga Byte) = 230 or 109
1024 GBs (1000) = 1 TB (Tera Byte) = 240 or 1012
1024 TBs (1000) = 1 Petabyte (PB) = 250 or 1015
1024 PBs (1000) = 1 Exabyte (EB) = 260 or 1018
1024 EBs (1000) = 1 Zettabyte (ZB) = 270 or 1021

Bit: Abbreviation of binary digits (0 or 1), the smallest unit of data storage. One bit occupies one storage location.
Essential Features (Compliments) of the Computer:
1. Hardware
2. Software
3. Human ware
Hardware: -
Only Physical parts of the computer, which can be seen and realize (touch) is known as Hardware. It is just a mechanism of the computer.
Software is nothing but the computer programs. Software is the set of programs, which are used for different purposes. It is also defined as the program concerned with the operation of the hardware in a data processing system.
Type of Software:
The software available in any computer system can be divided into two types.
1. System Software.
2. Application Software.
System software:
The software required for running user programs is known as system software. System software is the collection of the programs written for Computer, which allows the user to develop and run programs. The system software is provided along with the Computer itself and is stored in ROM/Disks.

Mainly, system software is divided into three parts:
System software
i) Operating System Program -
ii) Utility Program -
iii) Language Processor

Operating System Program:
Operating system is a program, which controls overall operations (activities) of the computer. It is the media point between the computer and operator. DOS, Unix, Windows are the examples of operating system.
Utility Program :
Utility programs are those programs, which are used for managing files or folders working with files or folders or drives and developing/writing and testing the programs.
Language Processor:
Language processor is that program, which translates the program written in programming language into an executable program (Human understanding language) that is understood and followed by hardware of the computer. Assemblers, compilers and interpreters are the examples of Language processor.
Application Software
The software written for special purpose (specific use) in a specific language is known as Application software these programs perform certain task with respect to related program. Ms. word, Ms. Excel, Ms. PowerPoint, Adobe PageMaker, Freehand, Photoshop, Ms. Access, dBase, Auto Cad are the examples of Application software.

Human ware
Person, who operates (handles) Computer and its periphery, is known as Human ware. It is also sometimes called computer personnel.

Types of computer (Classification of computer):
Up to now, there is no clear-cut classification of computer. However, Computers are classified on the basis of different groups. These are as follows:
1. On the basis of working Principle (Function)
a. Analog Computer
An analog computer is that which measures continuous types of physical values such as temperature or pressure. We have seen many devices used as Analog device. Thermometer, Millimeter, Speedometer, Fuel & Price Indicator in Petrol Pump are the examples of Analog Computer.
b. Digital Computer
The computer which accepts discrete data (discontinuous data) is known as digital computer. Basically, digital computer counts digits, which represent numbers or letters.
c. Hybrid Computer (Analog + Digital)
Hybrid computer is the combination of Analog and Digital computers. It has both features of Analog and Digital. It can do any types of tasks of Digital and Analog. They are mostly used in scientific research, industrial application, aeroplanes etc.
2. On the basis of size:
a. Super computer
Super Computers are 64-bit system with 100 MIPS (Millions Instruction per second) speed and 8 MB to 64 MB storage capacity. With the use of very high speed 1000 MB hard disk, its memory size has increased enormously. Super Computers use parallel processing technology instead of sequential or serial processing system.
b. Mainframe Computer
Mainframe computers are 32-bit, 45-bit, 64-bit machines and have 1 – 100 MIPS (Millions Instruction Per Second) as Processing speed. Mainframe computers are big which processes at high speed and occupies a big space. This has a big capacity of handling huge numbers of records.
c. Mini computer
Till the third generation, a 16-bit computer system with 512 KB memory and 20 MB removable hard disk used to be called a minicomputer.
d. Micro Computer
i) Desktop Computer
ii) Laptop computer (Briefcase size)
iii) Palmtop Computer
Micro Computer
Computers can no longer be classified as bit size. Micro Computer is also known as personal computer or home computer. They are made by using microchips (micro processor). They are extensively used at homes and offices. Many brands, models and sizes are available in microcomputer.
3. On the basis of Brand
a. IBM Computer (PC-Personal Computer
The computers manufactured by IBM (International Business Machine) company are called IBM Computers. The microcomputers of IBM company are called IBM PC. IBM is one of the leading company in computer manufacturing. These are reliable, strong and high processing speed.
b. IBM compatible
Computers, developed on the principles of IBM Computers are called IBM Compatible. It can perform all the tasks that an IBM computer does. They are less expensive than original (IBM) computers.
c. Apple/Macintosh
The computers manufactured by the Apple Company are called Apple Computers. They are specially used in Desktop-Designing. These are originals and quite expensive than IBM and IBM Compatible.
4. On the basis of Processing Speed (Processor used)
a. PC/XT (640 KB-4.77 to 8 MHz)
b. PC/At (640 KB - 8 to 10 MHz)
c. PC/AT 286 (1.2 MB-10 to 16 MHz)
d. PC/AT 386 (1.2 MB - 16 to 25 MHz)
e. PC/At 486 (4 MB - 25 to 33 MHz)
f. Pentium I, II, III, IV…
XT = Extra/ Extended Technology
AT = Advanced Technology
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