What Is Computer? Definition and their Components

A computer is an electronic device that accepts input data , processes it, stores it and outputs it for interpretation . The computer is part of a computer system . As the one illustrated below.


Computer Components : a computer system is made up of hardware, peripherals and software .

HARDWARE includes all electrical, electronic and mechanical devices (that can be seen and touched) that are used to process the data.

PERIPHERALS are the hardware devices found in the computer in order to increase the possibilities of access, storage and output of computer equipment. They include the Input devices and the Output devices .

INPUT DEVICES are peripherals whose function is to collect and translate the input data into a form that is acceptable to the computer. The most common input devices are the keyboard and the mouse or ” mouse “.

OUTPUT DEVICES are peripheral devices that represent, print or transfer the results of processing, extracting them from the main memory of the computer. Among the most used output devices are the Monitor or Screen and the Printer .

SOFTWARE – or programs – is the set of electronic instructions for controlling computer hardware. Some Programs exist for the Computer to use them as support for the management of their own tasks and devices. Other Programs exist for the Computer to service the User. For example, the creation of electronic documents that are printed.

DATA refers to the raw elements ( raw material ) that the computer can manipulate, to convert them into results or processed data, known asinformation ( finished product ). The data may consist of letters, numbers, sounds or images . Regardless of the type of data they are, the computer converts them into numbers to process them. Therefore, the computerized data is digital, which means that it has been reduced to digits or numbers. The data is stored on auxiliary storage media as part of files .

COMPUTER FILES are interrelated data sets to which a name has been assigned. A file that contains data that the user can open and use is often called document. A computer document can include many kinds of data, such as: A text file (such as a letter ); a group of numbers (such as a budget ); a fragment of video (including images and sounds, as a “video clip”). Computer programs (software) are also organized in files, but because they are not considered text, they are not document files.

USER is any person who interacts with the computer to provide input data or to obtain results from the computer system, which are normally displayed on the screen or printed through the printer.

Exploration of the functions of the computer: Two components handle the processing of data in a computer: the Central Processing Unit or CPUand the Main Memory RAM . Both components are located on the main system board or motherboard , because it is the board circuitry that connects the CPU to all other hardware devices.

Central Processing Unit or CPU : It is the brain of the computer, since it manipulates the data. On a personal computer or PC, the entire CPU is contained in a small chip called a microprocessor . Each CPU has two main parts: the Unit of Control ( Control Unit ) and Aritmético- Unit Logic ( Arithmetical-Logical Unit ALU ).

Control unit: It is the center of administration of the resources of the computer (such as a tax transit). The Control Unit has instructions or set of instructions incorporated . These list all the operations that the CPU can perform. Each instruction in game instruction is expressed in microcode,which consists of a series of basic directions that tell the CPU how to perform more complex operations.

Arithmetic-Logical Unit: In this Unit the Arithmetic Operations (Sum “+”, Subtraction “-“, Multiplication “x”, Division “/”, Raise to Power “^”) and Logical Operations such as equal to, not equal to; greater than, not greater than; less than, not less than; greater than or equal to, not greater than or equal to; less than or equal to, not less than or equal to.

Many instructions made by the Control Unit involve only moving data from one place to another; from RAM to Auxiliary Storage (for example Hard Disk ); of RAM to the Printer or the Screen and so on. However, when the Control Unit finds an instruction that implies arithmetic or logic, it passes that instruction to the Arithmetic-Logical Unit or UAL. In the UAL there is a group of registers , which are high- speed memory locationsbuilt directly on the CPU, which are used to preserve the data that is being processed at that moment. For example, the Control Unit could load “two numbers from the RAM Memory” to the registers of the ULA. Then you could ask the ULA to “divide the two numbers” (an arithmetic operation) or “determine if the numbers are equal” (a logical operation).

Main Memory or RAM (Random Access Memory ): It is the main storage device in real time where data and programs are stored while they are being used. The RAM consists of chips, either in the Motherboard or in a small circuit board connected to it. The CPU contains the basic instructions necessary to operate the computer, but does not have enough capacity to store entire programs or large data sets permanently, so it relies on RAM for this important function to store and retrieve data very quickly .

The RAM is random access and volatile in nature because it loses its contents when the computer is turned off. The CPU is connected to two kinds of memory: RAM that is volatile, and ROM , which is non-volatile (it keeps the data it contains, even when the computer is off).

Classification of computers and computer networks : Computers according to their size and price are classified into four major categories, namely: Microcomputers, Minicomputers, Mainframes and Supercomputers .

Microcomputer or PC: It is the most common type of computer, that is why it is called Personal Computer, because it is designed to be used by only one person at a time. Despite its small size, the modern PC is more powerful than any of the computers of the 1950s to 1960s. (See Figure 1). They have become so fundamental to 21st century society that without them the world economy would stop. They are tools so flexible and powerful that most people in the world of economic activities in the public, private sectors, NGOs , Cooperatives , SMEsThey use them normally. Even if you do not work in an economic entity, computers affect us every day. Every time we go to the bank , renew a subscription, request information from a phone number, etc., we are benefiting with the power and speed of computers. Even when we buy groceries, medicines, or gasoline, we interact with computers.

Minicomputers They are somewhat larger than PCs and are almost always used by companies and institutions in specific ways, such as payrollprocessing . These devices can execute the tasks of many users from a CPU Central to which terminals are connected which are input and output devices (similar to a PC but without computing capacity), equipped with a keyboard, a screen and the cable. Connection to the CPU Central. They transmit the process requests to the Minicomputer, which performs the process of the data and sends the result to the corresponding terminal. The Minicomputer Printer performsPrint job for all users connected by terminal. The Minicomputer Storage Device contains the data for all users in one place. The Minicomputers tend to disappear before the growth of computing capacity distributed in the Computer Networks .

Mainframes or Central Computers: They are large, fast and quite expensive. Frequently, they are used by private companies and government offices to centralize the storage, processing and administration of large amounts of data, and be able to provide this data at the request of many connected users. They are the preferred system when they are required: reliability, data security and centralized control. The central computer executes processing tasks for many users, who introduce their requests from their terminals . To process large amounts of data, they usually have multiple CPUs: One CPU manages the general operations, another CPU manages the communication with all users requesting data; a third CPU locates the data requested in Databases.

Supercomputers: They are the largest, fastest and most expensive type of these devices. Contrary to Minicomputers and Mainframe Computers, they are not designed to optimize the processing of multiple users; they use their great computing power in the solution of very complex problems , such as predicting the weather , modeling nuclear reactions, or controlling space flights. The speed of a Supercomputer can exceed the “billions of instructions per second”.

Computer networks: A network is a set of computers and other devices that communicate with each other to share data, hardware and software. In companies, networks have revolutionized the use of computer technology , to the point that there is a growing tendency to replace Mainframe computers and their terminals with Computational Networks in which each employee who needs a computer to work has a computer personal connected to the network . Now, computer technology and the ability to use them “are no longer centralized in the Mainframe computer and the Personnel of the IT Departmentand Systems “ of the companies that use the New Technologies of Information and Communication

(NTIC). The technology and the ability to use it are distributed within the organization through a network of computers and computer-trained users. In education , they have also changed to strategies designed based on personal computers in the network. This includes Local Area Networks ( LANs ) within a relatively limited area, such as a building or a university , where computers and printers are connected in a computer lab , and Wide Area Networks (WANs) that encompass a large area. geographic area between cities, regions, or countries, as is the caseInternet . The four great benefits involved in the use of Computational Networks are:

Allow simultaneous access to very important programs and information (Without a network that allows file sharing employees have to keep separate copies of information on different hard drives, information that becomes very difficult to update).

• Allow people to share peripheral equipment, such as printers and scanners.

Make personal communication more efficient through email


• Facilitate the backup process (In public and private organizations the information is extremely valuable, so it is imperative to have the security of the employees backing up their computerized information.) This is operationalized through a common storage device to which users can access through a network based on the respective authorization levels).

Description of peripheral devices in a computer : Peripheral devices are hardware components that accompany a computer to increase its functionality to enter, extract and store data. They are located “around the machine”. For example, the mouse or mouse, the keyboard, the monitor, the printer, bar code readers, hard disk, etc. The Peripheral devices are installed based on user needs and economic disponibilades. A typical Basic Equipment that is purchased, includes: Processor , RAM, Hard Disk, Floppy Disk Unit, Monitor, CD-ROM, Printer, Keyboard and Mouse. Any additional Peripherals that are required “are paid separately”. You could replace the mouse with a “Sphere Tracker” or Track Ball.

It is also possible to increase the capabilities of the computer by adding a Digitizer or Scanner to capture images. For Internet connection, it is required: Network Card , Modem and an Internet Access Service Account through an Internet Service Provider (ISP). So the configuration possibilities of the Basic Computer Equipment are very broad, depending on how much money you are willing to invest.

Pointing Devices (Mouse, Sphere and Pencil): These are devices that help manipulate objects and select menu options on the screen. The best known is the mouse or mouse as a pointing device in the Basic Computing Team.

To handle the Mouse or Mouse, rest the palm of the right hand on it , so that the index finger is on the left button . Hold the mouse with the thumb on the left side, the middle finger on the right button and the remaining two fingers, ring finger and little finger, holding the right side of the mouse. Try it now on your computer.

mouse pointer or pointer (usually in the shape of an arrowhead) moves across the screen “in accordance with the movements of the mouse” on a hard surface, preferably a ” mouse pad ” or mouse pad , on the surface from the desk.

The mouse has three fundamental operations, namely:

1. Click on the mouse : it is the operation of “pressing the left button once” to select an object on the screen.

2. Double click on the mouse : it is done by “pressing the left button twice in rapid succession” in some operations with the mouse it is required to double click.

3. Drag with the mouse : it is a combined operation of “Click and Drag an object from one place to another on the screen”. To do this: a) Place the Mouse Pointer on the object to be dragged; b) Press the left mouse button and “keep it pressed”; c) Move the mouse in the direction of drag

on the screen to “pull or drag the object to its new place”; d) Release the mouse by lifting the “right index finger of the left mouse button”.

Assuming you are working on a Personal Computer or PC *

Exercises with the Mouse in the Graphical User Interface (GUI):


1. Select the Start button on the taskbar of the desktop .

2. Select in the Programs Option the Text Processing Software that is installed on the PC you are using.

3. In the Menu FILE to click on the icon: New Blank Document

(If you have been successfully completed steps 1, 2 and 3, it should now be displayed on the screen “window Work to create a new document” if so proceed to Step 4 of this exercise; otherwise in all aspects repeat Steps 1, 2 and 3 until doing it correctly.

You can request help from the Computer Lab Facilitator or its equivalent )



4. Proceed now with the preparation of an Essay about the Characteristics of the Active Desktop in your Computer under the following conditions:

to. Document Size: Maximum 2 Letter-size pages.

b. Font Type: Times New Roman 12

c. Spacing: Double space

d. In the Essay find the answers to the Seven Dwarves of the

Research :

i. What or who…?

ii. Where…?

iii. How…?

iv. When…?

v. Which one…?

saw. For what…?

vii. Why…?

5. Save the Document with the File Name: Active Desktop

6. When you have completed Steps 1, 2, 3, 4, and 5, notify the Computer Lab Facilitator so that he or she can complete the Work or Expedited Test Certification.

The trackball or “Track Ball”

It is an alternative pointing device to the mouse. It works like a head mouse.

The user rests his thumb on the exposed ball and his fingers on the three buttons. To move the Pointer across the screen, the ball is rotated with the thumb.

Because the entire device does not move, a track ball requires less space than a mouse; so that when available space is limited, a track ball can be a “tailor-made” solution. These devices became popular with the advent of laptop computers , which are often used on the knees or on small work surfaces with no room for

mouse For example, in the seat of an airplane.

Trackballs, just like mice, are available in different models . On laptops, trackballs can be incorporated directly into the keyboard, slide out of the system unit into a small drawer, or be clamped to the side of the keyboard.



Electronic pencil

Although the keyboard and mouse are the most used input devices when working on the desktop, there are other ways to enter data into a computer.

Sometimes, the tool is just a matter of the user’s preference. However, in many cases, the usual tools may not be appropriate. For example, in a factory or warehouse full of dust, a mouse or keyboard can get clogged with dirt very soon.

The computer systems based on pencils use an electronic pencil as their main input device. The user holds the pencil in his hand and writes on a special pad or directly on the screen (when it is sensitive to touch)

Study of keyboards

The keyboard is the main input device for entering text and numbers into the computer. It consists of more or less 100 keys, each of which sends a different character code to the CPU.

Personal computer keyboards come in many styles. The different models differ in size, shape and feel, but with the exception of a few keys for special purposes, most keyboards have an almost identical arrangement. The most common arrangement is the one known as “Extended IBM Keyboard”.

It has 101 keys arranged in five groups , as shown below.

The keyboard of a PC



1. Alphanumeric keys (Alphanumeric keys)

2. Modifier Keys (Modifier keys)

3. Numeric keypad (Numeric keypad)

4. Function Keys

5. Keys Movement Cursor (Cursor movement keys)

Alphanumeric keys (Alphanumeric keys)

They are similar to the keys of a typewriter, both in its appearance and in its accommodation. This common accommodation order is called ” QWERTY layout”

because the first six letters in the top row are precisely Q, W, E, R, T, Y. In addition to letters, numbers and include signs of punctuation and symbolsspecial (, #, $,% ,&,/, etc.).

Modifying keys (Modifier keys)

They are keys that are used in combination with the keys of the alphanumeric keyboard, to execute operations of “keyboard shortcuts” or equivalents of menu options of the interface with the user. On a PC the modifier keys are: Shift, Ctrl, and Alt.

Numeric Keypad (Numeric keypad)

It is located on the right side of the keyboard, it looks like a calculating machine, with its ten digits and its mathematical operators (+, -, *, / ). This keyboard is preferred by cashiers, to make numerical data entries.

Function Keys (Function keys)

The Function Keys (F1, F2, …, F12) are generally arranged in a row along the top of the keyboard. They allow you to give commands to the computer “without typing long series of characters”. The purpose of each function key depends on the program or software being used. For example, in most programs the F1 Key is the key to request contextual “Help”. When pressed,

A Screen with information about the program that is being executed is displayed.

Cursor movement keys

These are keys that allow you to move the cursor on the screen up, down, right, or left. In a Word Processing Program, there is a mark on the screen where the characters you type will be entered. This mark receives the name of cursor or point of Insertion , can appear in the INSTRUMENTAL COMPUTERS


Screen like a box, a line or a symbol that looks like an uppercase I , known as an I- shaped cursor.

Other Keys (Esc, Print Screen, Scroll Lock, Pause)

Esc Usually, it is used to “go back” one level in a multilevel environment . For example, if several Dialog Boxes are opened , one from the other, you can press the Esc key to close them in reverse order.

Print Screen This key sends an ” image ” of the content of the Screen directly to the printer. It only works when there is a display in “text mode on the screen”; it does not work with Graphics Programs or in Graphic Environments.

Scroll Lock Normally, this key controls the functions of the cursor movement keys. With some Programs, Scroll Lock causes the cursor to remain stationary on the screen, and the content of the document to move around it. When Scroll Lock is disabled , the cursor moves normally.

This key does not work at all in some Programs.

Pause In some Programs, this key can be used to stop the execution of a “command in progress”.

How does the computer accept entries from the keyboard?



Press the key on the keyboard






SEND Code of

Digitization of the key

a Memory of

Keyboard (BUFFER)

Keyboard Controller

Send a Request for

Interruption to Software

of the system

System Software responds to the

Interruption reading the Code of

Digitization to CPU

System Software

Pass Code of

Digitization to the CPU

Study of Graphic Interfaces “Friendly with the User” (Gui)

In order to achieve the ” instrumental domain or correct handling of the computer” it is necessary that the User communicates with it; he should tell him what tasks he has to execute; accurately interpret the information presented on the screen.

Interface with the user is the means of communication of the human being with the machine.

Through this interface, the computer “accepts the entries” and “presents its outputs”.

These outputs provide:

?? the results of processing,

?? confirm the termination of the processing or

?? indicate that the data was already stored

The three most popular User – Computer communication means of the interface are:

1. Prompts

2. Attendees

3. Command line interface

Prompt is an orientation message, which the computer presents through the Screen,

to ask the User to do something. Some are easy to understand, such as:

“Type your full name”

Others may be incomprehensible to Casual Users, for example:

“C:> _”

To respond to a Prompt the User must enter the requested data or follow an instruction “verbatim”.

Suggestion Dialog is a “Prompts sequence” that is sometimes used to develop an interface with the User.

Attendees are ease of use provided by Modern Business Programs instead of Suggestions Dialogues. An Assistant is a succession of Screens that direct the User through several stages, such as:

Establish the Internet connection,

Create a Business Graph ,

Start a Scanner, etc.

Command is an instruction for the computer to execute a certain task or job.

An interface that asks the User to type commands is known as the Command Line Interface with the User. Each word of a command gives rise to aspecific action on the part of the computer.



The Commands that are entered must correspond to a specific syntax. The syntax denotes the “succession of words and punctuation commands, parameters and switches”. If the User “miswrites a command word” or if “omits the required punctuation” or “typs words out of order”, an error message or syntax error will occur . The process will continue after the User types the

command in correct form.

Menu is a List of Commands or Options that helps to reduce the difficulties of many Users “who find it very complicated” to remember the words and the syntax of the commands for the interfaces of command lines with the User . Simply choose the menu command so that the computer executes the corresponding task. Generally, two methods are used to introduce you to the

User “reasonable list of menu options”: One uses Hierarchies and the other boxes Dialogue .

Hierarchy of Menus is an ordering of Menus classified into a superior-subordinate relationship, as in an organization chart . After selecting an option in a Main Menu, a submenu appears in which you can make more selections by pointing to an option of it, and so on in order of hierarchical descent.

Dialog Box or Dialog Window presents the options related to a command that appears as “Option in a Menu”, for example in the File Menu the option Print … (Print …) shows three ellipses to indicate that it leads to a Dialog Box

Exercise : Practice the File Menu Navigation on your Computer or PC Lab.


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