Computer Hardware

Computer Hardware

[ From chapter-4 of the book "Information Technology in Banking" written by Abul Kashem Md. Shirin and Nusrat Tamanna Prianka and published by Institute of Bankers, Bangladesh (IBB) ]

Computer is an electronic device which quickly and accurately processes the data and information supplied by human using logic and formula given by human to output result for human being. Human beings undertake decision based on this output.

1.         History of Development of Computer

Computer is the result of research of hundreds of years. Development of computer starts with the invention of counting machine by various mathematicians like John Napier (1550 – 1617), Blasé Pascal (1642) and Leibniz (1671). Charles Babbage (1792 – 1871), a mathematician of England, developed Difference Engine in 1821. In 1833, he started developing another counting machine in the name of “Analytical Engine”, but could not complete before his death. Design of his Analytical Engine is the basis of modern Computer. This is why Charles Babbage is terms as the “Father of Computer”.

Professor D. John Atanasoff of United States developed an electronic Computer named ABC using vacuum tube in 1942. Later on in 1946, Professor Dr. John Mauchly and his student Engineer Presper jointly developed a computer named ENIAC (Electronic Numeric Integrator And Calculator) on which there were 1800 valves. Its weight was 30 tons, and an electric load of 150 KW was required to run it. These two scientists developed another computer in the name of UNIVAC (Universal Automatic Calculator) in 1951 which had Input, Output and Memory units. This was the first electronic computer produced commercially.

In 1954, the IBM (International Business Machine) company of United States produced a Computer in the name of IMB-701 and starts business.

Bangladesh Atomic Energy Commission installed first computer in Dhaka in 1964. It was an IBM-1620 mainframe computer. Thereafter Bangladesh University of Engineering & Technology (BUET), Bangladesh Bureau of Statistics, Power Development Board installed mainframe computer for their uses.

In 1971, the Intel Company of United States developed MSC-4 microprocessor and introduced Microcomputer.

Due to its development and commercial availability, we can see the use of Microcomputers in educational institutions, business organizations, offices and houses.

2.         Generations of Computer

Computer can be divided into following four generations:

1^st Generation (1951 – 1958):

Characteristics: Use of Vacuum Tube or Vacuum Valve, Big in size, Capability to store program and information, Use of Magnetic Drum, Punch Card and Magnetic tape. Example: ENIAC, MARK, IBM-650. 

2^nd Generation (1958 – 1965):

Characteristics: Use of IC (Integrated Circuit), Use of transistor instead of Vacuum Tube, Small in size, introduction of ACCII code, development of high-level language like COBOL, FORTRAN and ALGOL. Example: IBM-1620, CDC-1604, NCR-300.

3^rd Generation (1965 – 1971):

Characteristics: Introduction of Mouse as input device, Small in size, reduction of price, Introduction of VDO unit and Printer as output device, use of secondary memory, invention of BASIC language, word processing and other applications. Example: IBM-370, PDP-II.

4^th Generation (1971 – to date):

Characteristics: Invention and use of Microprocessor, Semi-Conductor memory, ROM, RAM, PROM, EPROM, Higher capacity of storing information, Development of operating systems like DOS, MAC, Windows and Unix, development of various application software and programming languages, development of Super Computer, Laptop, Notebook, Desktop and Personal Computers. Example: PC, Sever and Laptop of various brands such as IBM, Compaq, HP, Sun, Dell, ACER.

3.         Types of Computer

Based on the nature of jobs, the Computer can be divided into following three types:

1.      Analog Computer

2.      Digital Computer

3.      Hybrid Computer

Analog Computer is used for special purposes such as measuring pressure and temperature, supply of petrol in petrol pumps and determining price, and controlling speed of a vehicle or Airplane.

Digital Computer works in line with the principles of mathematics. It works using binary systems, i.e., using 1 and 0. The Computers we use at home and office are all Digital computers.

Hybrid Computer collects data from various systems using analog process, but processes the data in digital system.

Based on size and capacity, Computers (or Digital Computers) can be divided into four types as under:

1.      Super Computer

2.      Mainframe Computer

3.      Mini Computer

4.      Micro Computer

Super Computer is very powerful. It requires less time to complete mathematical processes. Super computer is used in scientific research, for processing of large volume of data, for controlling missile, space research, design of nuclear plant. CRAY-1, Super SxII, CYBER-205 are the example of Super Computers.

Mainframe Computer is very large in size. Connecting many small computers into it, many people can work together in a Mainframe Computer. It is used in large organizations like Banks, Insurance Companies and Universities. IBM4300, UNIVAC 1100, NCR 8370 are the example of Mainframe Computers.

Mini Computers are smaller and less costly than Mainframe Computers. Many people can also work in a Mini Computer together using terminals connected to it. Relatively smaller Banks, Insurance Companies, Industries, Educational Institutions and Research Organizations use Mini Computers. IBM S/34 and NCR S/9290 are the example of Mini Computers.

Microcomputers are very small, cheap and widely used computer. As microprocessor is used in this type of computers, they are termed as Microcomputer. Only one person can work at a time in a Microcomputer. For this they are also known as Personal Computer or PC. Microcomputers are used at home and office for personal and official purposes. They are also used for entertainment purposes like playing games, viewing video, listening songs, and browsing internet. IBM PC, Apple PC and Macintosh PC are the example of Microcomputers.

4.         Computer Hardware and Devices

The devices of a computer may be divided into five parts, like:

Input devices

Output devices

Processing devices

Memory devices

Special devices

4.1.      Input devices

The devices or parts of the computer used for inputting information, data and instruction into the computer are known as Input Devices. Keyboard, Mouse, Joystick, Scanner, Digital Camera, Microphone etc are the example of input devices.

Keyboard: A Keyboard is a device that contains 104 to 110 number of keys. These keys are used for typing letters and digits and providing instructions to the computer. A keyboard is connected to the motherboard of a computer using a cable.

Mouse: A Mouse is a device used as alternative or associated equipment for providing instruction to the computer having windows or Macintosh operating system in it. The mouse has 2 or 3 buttons.

4.2.      Output devices

The devices which are used for communicating result to the users are called Output Devices. Monitor, Printer, Speaker and Plotter are the example of output devices.

Monitor: The result of processing activities on certain supplied information and data is displayed using text, graph or picture on a TV like device called Monitor. The Monitor is connected to the system board of a computer using a data cable. In some monitors, a separate power connection is required.

Printer: The output of a computer is printed on paper using a device called Printer. Printer is connected to the computer’s system board using a data cable. Power is supplied to the printer using another cable.

Printer is of two types – Dot Matrix Printer and Laser Printer. Dot matrix printer has a “Head” which creates impact on a ribbon. The ink on the ribbon produces letter, special character and digit on the paper. Epson dot matrix printer, Epson line printer are the example of dot matrix printer. In the Laser Printer instead of Head, laser ray is used to produce letter, special character and digits. Ina Laser Printer, instead of ribbon, a Tonner or Cartridge is used for supplying ink. Ink Jet Printer and Canon Laser Printer are the example of Laser Printer.

Speaker: Speaker is used for creation of sound during listening songs or viewing video.

Plotter: A Plotter is used for printing a drawing from computer. Plotter is also used for printing large picture, poster, calendar and map.

4.3.      Processing Devices

The devices used for processing of supplied information, data and instructions in a computer are called Processing Devices. CPU or Central Processing Unit is a processing device used in computer. It performs all the processing activities of a computer. CUP is like the brain of human being. The speed and capacity of processing of a computer depends on its CPU.

In 1971, the Intel Company invented microprocessor for use in computer. It was called as 8008 microprocessor. Thereafter Apple produced microprocessor in 1976 and IBM in 1981.

The functionalities of a CPU are stated below:

1.      CPU sends controlling and time determining signals to all parts of the computer.

2.      Send and receive data between memory and input/output devices.

3.      Receive data and instructions from memory.

4.      Decode the instructions.

5.      Perform mathematical and logical activities.

6.       Run program from computer memory.

7.      Coordinate between input and output devices.

Based on the architecture, a microprocessor can be divided into 2 groups like CISC processor and RISC processor.

CISC or Complex Instruction Set Computer is a microprocessor which uses microcode. Microcode consists of some instructions (software program) which work from inside the chip. As this type of microprocessor run by software, they are normally slow. Examples of CISC microprocessor are: 8085, 8086, 8088, 80286, 80386SX, 80386DX, 80486SX, 80486DX and Pentium of Intel, 386DX, 486DX of AMD, 6800, 68000, 68040 of Motorola.

RISC or Reduced Instruction Set Computer is a microprocessor in which less number of instructions sets are used. It is not software based, rather hardware based and as such faster than the CISC processor. Banks normally uses RISC processor-based computers as its main database server in the data center. Unix is normally used as operating system of such RISC servers. For example, AIX is used as operating system for IBM RISC servers, Sun Solaris for SUN RISC servers and HP-UX for HP RISC servers.

4.4.      Memory Device

Memory devices are the devices where the computer temporarily or permanently stores the data before, during and after processing. The memory devices can be categorized into 3 groups: Primary or Main memory, Cache memory and Secondary or Auxiliary memory.

4.4.1.   Primary or Main memory

The memory directly connected to the CPU is called Primary or Main Memory. It is used to store program, data, instructions and result during execution. RAM and ROM are the example of such memory.

RAM: RAM stands for Random Access Memory. Computer read all the relevant data, program and instructions from the input devices or permanent storage and writes into the RAM for processing. RAM has the following characteristics:

1.      RAM is volatile in nature

2.      It is a read-write memory

3.      During processing the information stay in RAM

4.      If power fails, all the information removes from the RAM.

ROM: ROM stands for Read Only Memory. ROM stores a program called BIOS (Basic Input Output System). List, position and specification of all the devices of a computer are recorded into the BIOS. Computer at the time of startup recognizes all the devices with the help of BIOS. The characteristics of a ROM are as under:

1.      ROM is a permanent main memory.

2.      The information in the ROM can only be read, can’t be modified.

3.      The programs required to startup a computer are stored permanently in the ROM

4.      If power fails, the information at ROM does not vanish.

4.4.2.   Secondary or Auxiliary memory

The memory which is used to store the user program and information permanently is called Secondary or Auxiliary memory. Examples are: Floppy Disk, Hard Disk, Compact Disk, Magnetic Tape, Pen Drive etc.

Floppy Disk: A light and small disk which is produced by putting a magnetic layer on a thin plastic sheet is called Floppy Disk. The information and program are stored in Floppy Disk. Normally floppy disk is used to transfer information from one computer to another. Floppy disks are of two sizes – 3.5” and 5.25”. The device used to read and write information from/to floppy disk is called Floppy Drive. Floppy Drives are also available in two sizes – 3.5” and 5.25”.

The capacity of the 3.5” floppy disk is 1.44 MB and that of 5.25” floppy drive is 360 KB.

Due to invention of Pen Drive, the use of Floppy Drive has become unpopular.

Hard Disk: A hard disk is connected inside the computer box using screw and data & power cables, and has much higher capacity and speed than the floppy disk. The data and programs are normally kept stored into the hard disk. No drive is required in the computer for use of hard disk. Hard disk of various capacity is available in the market like 250 GB hard disk, 500 GB hard disk etc.

Compact Disk: Compact Disk is called CD in short. CD is used for recording or storing data, program, song, game, video etc. and also for transferring data from one computer to another. Some CD only allows reading Information from it. The information in it can’t be modified. Also new information can’t be added into these CD. These CDs are called CD-ROM (Read Only Memory). The drive connected to the Computer and used to read information from CD is called CD Drive. There are some CDs which allow reading, modifying and adding information. These CDs are called Re-Writable CD (CD-RW). For reading, modifying and adding information into a CD-RW, a device is connected with the computer which is called CD Writer. A CD is like a circular disk having a diameter of 4.75”. A CD has a capacity of 650 MB.

Magnetic Tape: Magnetic Tape is a plastic reel covered with iron oxide and wrapped in a cassette. Magnetic Tape is used for backing up useful data from hard disk to the tape. This ensures that the data will be available in case of damage of the hard disk. Making duplication of data from hard disk into a magnetic tape is called Backup. Bank daily creates a makeup copy of customer data. A device is connected with the computer using a data cable and used to copy data from computer hard disk to tape drive. This device is called as Tape Drive.

Pen Drive: A Pen Drive is a data storage device which is physically much smaller than a floppy disk but can store mush higher capacity of data like 2GB, 4GB, 8GB and up to 256 GB. They are more durable and reliable because of their lack of moving parts. A Pen Drive is also called as USB flash drive because it is equipped with a USB (Universal Serial Bus) connector at one end. The connector is inserted into the USB port on a computer and the files or data can be copied from/to the pen drive.

4.4.3.   Cache memory

A special memory placed with the CPU or main memory to increase speed of processing is called Cache Memory. Cache Memory can be classified into two types – Internal Cache and External Cache. Internal Cache is placed inside the microprocessor whereas the external cache is placed on the mother board as IC (Integrated Circuit).

4.5.      Special Devices

Special devices are devices used to interconnect input, output and memory devices. System Box, Mother Board, Power Supply Unit are the example of special devices.

System Box: A box where the mother board, hard disk, floppy disk, CD drive and power supply unit are connected using screw and cable, is called System Box. Many people wrongly call the system box as CPU. A system box connected with all the required devices, a monitor, a keyboard and a mouse constitute a computer.

Mother Board: A device which is connected to the system box using screw and which has various slots over which the CPU (processor), ROM and RAM are connected directly, is called Mother Board. The Mother Board has also various ports to which the keyboard, mouse, monitor, floppy drive, CD drive and printer are connected using cable. There are thousands of wires placed inside the mother board which connects various devices internally and carry data and signal from one device to another device. These wire system is called Bus System.

Power Supply Unit: A Power Supply Unit is the component that supplies power to the other components in a computer. More specifically, a power supply unit is typically designed to convert Alternating Current (AC) to Direct Current (DC) which is required for the various components of the computer.

UPS: UPS stands for Uninterrupted Power Supply. UPS is an electrical apparatus that provides emergency power to a computer when the input power source fails, thus protect Computer from sudden shutdown. The UPS can be of two types – Online UPS and Offline UPS. Online UPS has zero transfer time and used with servers, while the offline UPS has a transfer time of 5-10 ms. Both the types of UPS can protect the computer from shutting down in case of power failure, but the online UPS, in addition, can protect data from being garbage/damaged due to power fluctuations as this type of UPS require no transfer time for switching between main power to batter power.

Voltage Stabilizer: A Voltage Stabilizer is an electric regulator designed to automatically maintain an output of constant voltage level irrespective of variation in input voltage. The Voltage Stabilizers are used with Computer System to protect the computer from sudden fluctuation of voltage.