Power on Self Test.

IBM 1401, IBM 1620, UNIVAC 1108

ENIAC, EDVAC, UNIVAC 1

The primary memory is used to temporarily store the programs and data when the instructions are ready to execute. The secondary memory is used to store the data permanently

(i) The ALU is a part of the CPU where various computing functions are performed on data.
(ii) The ALU performs arithmetic operations such as addition, subtraction, multiplication, division and logical operations.
(iii) The result of an operation is stored in internal memory of CPU.
(iv) The logical operations of ALU promote the decision-making ability of a computer.

(i) The transistor ("transfer resistance") is made up of semiconductors.
(ii) It is a component used to control the amount of current or voltage or used for amplification modulation or switching of an electronic signal.

(i) Vacuum tubes contain electrodes for controlling electron flow and were used in early computers as a switch or an amplifier.
(ii) Vaccum tubes are big in size and consumed more power.

Monitor:
(i) Monitor is the most commonly used output device to display the information. It looks like a TV.
(ii) Pictures on a monitor are formed with picture elements called PIXELS.
(iii) Monitors may either be Monochrome which display text or images in Black and White or can be color, which display results in multiple colors.
(iv) There are many types of monitors available such as CRT (Cathode Ray Tube), LCD (Liquid Crystal Display) and LED (Light Emitting Diodes).
(v) The video graphics card helps the keyboard to communicate with the screen.
(vi) It acts as an interface between the computer and display monitor.

(i) Parallel and Distributed computing
(ii) Computers have become smarter, faster and smaller
(iii) Development of robotics
(iv) Natural Language Processing
(v) Development of Voice Recognition Software

Impact printers:
(i) These printers print with striking of hammers or pins on ribbon. These printers can print multi-part (using carbon papers) by using mechanical pressure. For example, Dot Matrix printers and Line matrix printers are impact printers.
(ii) A Dot matrix printer that prints using a fixed number of pins or wires.
(iii) Line matrix printers use a fixed print head for printing.

(i) Scanner :
Scanners are used to enter the information directly into the computer's memory. This device works like a Xerox machine. The scanner converts any type of printed or written information including photographs into a digital format, which can be manipulated by the computer.
(ii) Fingerprint Scanners : 
Fingerprint Scanner is a fingerprint recognition device used for computer security, equipped with the fingerprint recognition feature that uses biometric technology. Fingerprint Reader / Scanner is a very safe and convenient device for security instead of using passwords, which is vulnerable to fraud and is hard to remember.
(iii) Monitor :
Monitor is the most commonly used output device to display the information. It looks like a TV. Pictures on a monitor are formed with picture elements called PIXELS. Monitors may either be Monochrome which display text or images in Black and White or can be color, which display results in multiple colors. There are many types of monitors available such as CRT (Cathode Ray Tube), LCD (Liquid Crystal Display) and LED (Light Emitting Diodes). The monitor works with the VGA (Video Graphics Array) card. The video graphics card helps the keyboard to communicate with the screen. It acts as an interface between the computer and display monitor. Usually the recent motherboards incorporate built-in video card.
(iv) Plotter :
Plotter is an output device that is used to produce graphical output on papers. It uses single colour or multi colour pens to draw pictures.

Components of a Computer :
The computer is the combination of hardware and software. Hardware is the physical component of a computer like motherboard, memory devices, monitor, keyboard etc., while software is the set of programs or instructions. Both hardware and software together make the computer system to function. Every task given to a computer follows an Input-process - output cycle (IPO cycle).

(i) Input unit: Input unit is used to feed any form of data to the computer, which can be stored in the memory unit for further processing.
Example : keyboard, mouse etc.
(i) Central Processing Unit : CPU is the major component which interprets and executes software instructions. It also control the operation of all other components such as memory, input and output units.
(iii) Arithmetic and Logic Unit : The ALU is a part of the CPU where various computing functions are performed on data. The ALU performs arithmetic operations such as addition, subtraction, multiplication, division and logical operations.

(iv) Control Unit : The control unit controls the flow of data between the CPU memory and I/o devices. It also controls the entire operation of a computer.
(v) Output Unit: An output unit is any hardware component that convey information to users in an understandable form. Example : Monitor, Printer etc.
(vi) Memory Unit: The Memory Unit is of two types which are primary memory and secondary memory. The primary memory is used to temporarily store the programs and data when the instructions are ready to execute. The secondary memory is used to store the data permanently. The Primary Memory is volatile, that is,the content is lost when the power supply is switched off. The Random Access Memory (RAM) is an example of a main memory. The Secondary memory is non volatile, that is, the content is available even after the power supply is switched off. Hard disk, CD-ROM and DVD ROM are examples of secondary memory.