Hard copy

Mainly computer system consists of three parts, that are central processing unit (CPU), <a href="https://www.tutorialandexample.com/input-devices-of-computer/">Input Devices</a>, and <a href="https://www.tutorialandexample.com/output-devices-of-computer/">Output Devices</a>. The Central Processing Unit (CPU) is divided into two parts again: arithmetic logic unit (ALU) and the control unit (CU). The set of instruction is in the form of raw data.

A large amount of data is stored in the computer memory with the help of primary and secondary storage devices. The CPU is like the heart/brain of the computer. The user does not get the desired output, without the necessary option taken by the CPU.  The Central processing unit (CPU) is responsible for the processing of all the instructions which are given by the user to the computer system.

                                       Fig: Block Diagram of the computer.

The data is entered through input devices such as the keyboard, mouse, etc. This set of instruction is processed by the CPU after getting the input by the user, and then the computer system produces the output. The computer can show the output with the help of output devices to the user, such as  monitor, printer, etc.

• CPU (Central Processing Unit)
• Storage Unit
• ALU(Arithmetic Logic Unit)
• Control Unit

1. Device management
   In a computer system, there is a tremendous speed mismatch between the CPU and the I/O devices. The job of an operating system is to maintain a balance between the CPU and I/O devices. Apart from this, it has to maintain a balance between various I/O devices and has to keep the CPU busy in various processing.
2. Processor Management
   A process or a job is an application program in running state. Processor management is the important part of an OS, which enables the activities of planning, monitoring and performing a process. During execution, a process needs certain resources such as CPU time, memory space, files and I/O devices.

PROM stands for Programmable Read Only Memory while EPROM stands for Erasable Programmable Read Only Memory, and EEPROM stands for Electrically Erasable Programmable Read-Only Memory.

PROM is a Read Only Memory (ROM) that can be modified only once by a user while EPROM is a programmable ROM that can be erased and reused. EEPROM, on the other hand, is a user-modifiable ROM that can be erased and reprogrammed repeatedly through a normal electrical voltage.

RAM: The full form of RAM is Random Access Memory. The information stored in this type of memory is lost when the power supply to the PC or laptop is switched off. 

ROM: The full form of ROM is a Read-Only Memory. It is a permanent type of memory. Its content are not lost when the power supply is switched off. The computer manufacturer decides the information of ROM, and it is permanently stored at the time of manufacturing, which cannot be overwritten by the user.

PROM: The full form of PROM is Programmable Read-Only memory. This type of ROM is written or programmed using a particular device.

EPROM: The full form of EPROM is Erasable Programmable Read-only memory. It stores instructions, but you can erase only by exposing the memory to ultraviolet light.

EEPROM stands for electrically Erasable Programmable Read-Only Memory. It stores and deletes instructions on a special circuit.

Monitor is an output device that receives processed information from the computer's CPU and displays it for the user.

Monitor is a computer peripheral, which is an electronic screen. The display in electronic form is called a softcopy. Monitor is also called as a visual display unit.   The display is made up of a series of dots called pixels.

Different types of monitors are:

Cathode Ray Tube (CRT)

CRT was in used until 21st century, but now they are phased out. It contains a vacuum tube that displays images using multiple electron guns and a phosphorescent screen.

Liquid Crystal Display (LCD)

LCD using liquire crystals to display images and the screen used is a flat panel of display.

Light Emitting Diode (LED)

LED uses semiconductor light source, where light is emitted when electricity flows through it.

Plasma Display

In a plasma display, each pixel is illuminated by plasma (also called as charged gas). It is thinner than CRT and LCD.

As a rule, specialists name three types based on what is inside them.

These types are:

CRT – Cathode Ray Tube

LCD – Liquid Crystal Display

LED – Light Emitting Diodes  

The word ‘computer’ has a very interesting origin. It was first used in the 16th century for a person who used to compute, i.e. do calculations. The word was used in the same sense as a noun until the 20th century. Women were hired as human computers to carry out all forms of calculations and computations.

By the last part of the 19th century, the word was also used to describe machines that did calculations. The modern day use of the word is generally to describe programmable digital devices that run on electricity.

Early History of Computer

Since the evolution of humans, devices have been used for calculations for thousands of years. One of the earliest and well-known devices was an abacus. Then in 1822, the father of computers, Charles Babbage began developing what would be the first mechanical computer. And then it 1833 he actually designed an Analytical Engine which was a general purpose computer. It contained an ALU, some basic flow chart principles and the concept of integrated memory.

Then more than a century later in the history of computers, we got our first electronic computer for general purpose. It was the ENIAC, which stands for Electronic Numerical Integrator and Computer. The inventors of this computer were John W. Mauchly and J.Presper Eckert.

And with times the technology developed and the computers got smaller and the processing got faster. We got our first laptop in 1981 and it was introduced by Adam Osborne and EPSON.

Speed

A computer works with much higher speed and accuracy compared to humans while performing mathematical calculations. Computers can process millions (1,000,000) of instructions per second. The time taken by computers for their operations is microseconds and nanoseconds.

Accuracy

Computers perform calculations with 100% accuracy. Errors may occur due to data inconsistency or inaccuracy.

Diligence

A computer can perform millions of tasks or calculations with the same consistency and accuracy. It doesn’t feel any fatigue or lack of concentration. Its memory also makes it superior to that of human beings.

Versatility

Versatility refers to the capability of a computer to perform different kinds of works with same accuracy and efficiency.

Reliability

A computer is reliable as it gives consistent result for similar set of data i.e., if we give same set of input any number of times, we will get the same result.

Automation

Computer performs all the tasks automatically i.e. it performs tasks without manual intervention.

Memory

A computer has built-in memory called primary memory where it stores data. Secondary storage are removable devices such as CDs, pen drives, etc., which are also used to store data.

Speed :A computer works with much higher speed and accuracy compared to humans while performing mathematical calculations. Computers can process millions (1,000,000) of instructions per second. The time taken by computers for their operations is microseconds and nanoseconds.

Accuracy:Computers perform calculations with 100% accuracy. Errors may occur due to data inconsistency or inaccuracy.

Diligence:A computer can perform millions of tasks or calculations with the same consistency and accuracy. It doesn’t feel any fatigue or lack of concentration. Its memory also makes it superior to that of human beings.

Versatility:Versatility refers to the capability of a computer to perform different kinds of works with same accuracy and efficiency.

Reliability:A computer is reliable as it gives consistent result for similar set of data i.e., if we give same set of input any number of times, we will get the same result.

Some of the limitations of computer are as follows:

• No Self-Intelligence. Computer does not have intelligence of its own to complete the tasks. ...
• No Thinking and Decision Making Power. The computer cannot think itself. ...
• No Feeling. Lack of feeling is another limitation of computer. ...
• No Learning Power.

  Advantages And Disadvantages Of Computer

• Multitasking. Multitasking is one of the major advantage of computer. ...
• Speed. Now computer is not just a calculating device. ...
• Cost/ Stores huge amount of data. It is a low cost solution. ...
• Accuracy. ...
• Data Security. ...
• Online Cyber Crimes.

A network consists of two or more computers that are linked in order to share resources (such as printers and CDs), exchange files, or allow electronic communications. The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.

Two very common types of networks include:

Local Area Network (LAN)
Wide Area Network (WAN)

A Local Area Network (LAN) is a network that is confined to a relatively small area. It is generally limited to a geographic area such as a writing lab, school, or building.

Computers connected to a network are broadly categorized as servers or workstations. Servers are generally not used by humans directly, but rather run continuously to provide "services" to the other computers (and their human users) on the network. Services provided can include printing and faxing, software hosting, file storage and sharing, messaging, data storage and retrieval, complete access control (security) for the network's resources, and many others.

Wide Area Networks (WANs) connect networks in larger geographic areas, such as Florida, the United States, or the world. Dedicated transoceanic cabling or satellite uplinks may be used to connect this type of global network.

Using a WAN, schools in Florida can communicate with places like Tokyo in a matter of seconds, without paying enormous phone bills. Two users a half-world apart with workstations equipped with microphones and a webcams might teleconference in real time. A WAN is complicated. It uses multiplexers, bridges, and routers to connect local and metropolitan networks to global communications networks like the Internet. To users, however, a WAN will not appear to be much different than a LAN.

In information technology, a header is, in general, something that goes in front of something else and is usually repeated as a standard part of the units of something else. A header can consist of multiple fields s, each containing its own value.  

OMR stands for Optical Mark Recognition. Its functioning is simple; it uses an optical scanner to detect marks on the paper.

Then, it is pre-calibrated in a way that the backend software can quickly determine the data fed into the system. So, based on where and at what position the marks are made, helps OMR determine the fed data results.

Optical Character Recognition (OCR) is used to identify the characters from a physical document. It compares the identified marks with the preset character rules.

The recognized figures are then compiled into an editable word document. OCR technology is extensively used for data entry purposes.

The word IT means information technology. On the other hand, for ITES, it refers to the all those services that are technology-enabled, or done with the help of technology.

The main objective was to enable business strategy through IT assistance and to use IT to achieve the goals of a business organization. It is highly applicable in IT, administration, HR and also in major call centre applications.