Basics in Computers

Classifications, generations, applications and limitations of digital computers


  • Computer Classification: By Size and Power

Computers differ based on their data processing abilities. They are classified according to purpose, data handling and functionality.

According to functionality, computers are classified as:

  • Analog Computer: A computer that represents numbers by some continuously variable physical quantity, whose variations mimic the properties of some system being modeled.
  • Personal computer: personal computeris a computer small and low cost. The term”personal computer” is used to describe desktop computers (desktops).
  • Workstation: A terminal or desktop computer in a network. In this context, workstation is just a generic term for a user’s machine (client machine) in contrast to a “server” or “mainframe.”
  • Minicomputer: minicomputer isn’t very mini. At least, not in the way most of us think of mini. You know how big the personal computer is and its related family.
  • Mainframe: It refers to the kind of large computer that runs an entire corporation.
  • Supercomputer: Itis the biggest, fastest, and most expensive computers on earth.
  • Microcomputer: A personal computer is a

According to purpose or functionality, computers are classified as general purpose and special purpose computers. General purpose computers solve large variety of problems.They are said to be multi purpose for they perform a wide range of tasks. Examples of general purpose computer include desktop and laptops.
On the other hand,special purpose computers solve only specific problems.They are dedicated to perform only particular tasks.Examples of special purpose computers can include calculators and money counting machine.


Generation of Digital Computers

According to age,computers are grouped in terms of generations. They include;1st generation computers,2nd generation computers,3rd generation computers,4th generation computers, and finally 5th generation.

1st  generation computers.This is a generation of computers that were discovered between the years 1946 and 1957.These computers had the following characteristics: They used vacuum tubes for circuiting.They used magnetic drums as memory for data processing.Their operating system was quite low as compared to the later generations.An operating system can be defined as a collection of programs designed to control the computer’s interaction and communication with the user. A computer must load the operating system like Microsoft into memory before it can load an application program like Ms Word.These computers required large space for installation.They were large in size and could take up the entire room.They consumed a lot of power.They also produced huge amounts of energy and power which saw machines breaking down oftenly. Using the computers,programming capabilities was quite low since the computers relied on machine language.Machine language can only be understood by the computer but not human beings .Their input was based on punched cards and paper tapes.

2nd  generation computers. These computers existed between the years 1958 and 1964.They possessed the following features:These computers used transistors for circuitry purposes.They were quite smaller in size compared to the 1st generation computers. Unlike the 1st generation computers, they consumed less power. Their operating system was faster.During this generation, programming languages such as COBOL and FORTRAN were developed.This phase of computers relied on punched cards too for input and printouts.

3rd generation computers.These are computers that existed between 1965 and 1971.The computers used integrated circuits(ICs) for circuitry purposes.The computers were smaller in size due to the introduction of the chip.They had a large memory for processing data. Their processing speed was much higher.The technology used in these computers was small scale integration (SSI) technology.

4th generation computers. The computers under this generation were discovered from 1972 to 1990s. The computers employed large scale integration (LSI) technology.The size of memory was /is high/large,hence faster processing of data.Their processing speed was high.The computers were also smaller in size and less costly in terms of installation.This phase of computers saw introduction of keyboards that could interface well with processing system.During this phase, there was rapid internet evolution.Other advances that were made included the introduction of GUI(graphical user interface) and mouses.Other than GUI, there exist other user interfaces like natural-language interface,question-and-answer interface,command line interface(CLI).


5th generation computers.These are computers that are still under development and invention. There development might have began in 1990s and continues in to the future. These computers use very large scale integration (VLSI) technology. The memory speed of these computers is extremely high.The computers can perform parallel processing. It is during this generation that Artificial Intelligence (AI) concept was generated e.g voice and speech recognition. These computers will use quantum computation and molecular technology.They will be able to interpret data and respond to it without direct control by human beings.


Applications and Limitations of Digital Computers

In a very general way, it can be said that the advantages of the digital computer compared to the analog computer,I are its greater flexibility and precision, while its disadvantages are its higher cost and complexity.

Information storage can be easier in digital computer systems than in analogue ones. New features can often be added to a digital system more easily too.


Computer-controlled digital systems can be controlled by software, allowing new functions to be added without changing hardware. Often this can be done outside of the factory by updating the product’s software. So, the product’s design errors can be corrected after the product is in a customer’s hands.

Information storage can be easier in digital systems than in analog ones. The noise-immunity of digital systems permits data to be stored and retrieved without degradation. In an analog system, noise from aging and wear degrade the information stored. In a digital system, as long as the total noise is below a certain level, the information can be recovered perfectly.

Digital computers play an important role in life today as they can be used to control industrial processes, analyse and organize business data, assist in scientific research and designing of automobiles and aircraf, and even help making special effects in movies. Some Main Applications of Digital Computers are as follows –

Recording Information

Official statistics keepers and some scouts use computers to record statistics, take notes and chat online while attending and working at a sports event.

Analyzing Movements

The best athletes pay close attention to detail. Computers can slow recorded video and allow people to study their specific movements to try to improve their tendencies and repair poor habits.


Many sportswriters attend several sporting events a week, and they take their computers with them to write during the game or shortly after while their thoughts are fresh in their mind.


The main disadvantages are that digital circuits use more energy than analogue circuits to accomplish the same tasks, thus producing more heat as well. Digital circuits are often fragile, in that if a single piece of digital data is lost or misinterpreted, the meaning of large blocks of related data can completely change.



Definition of digital computer, Elements of computer: Input unit, Output unit, Primary memory, Secondary memory and Processing unit.



  • Computer is an electronic device that is designed to work with Information. term computer is derived from the Latin termcomputare’, this means to calculateor programmable machineComputer cannot do anything without a Program. It represents the decimal numbers through a string of binary digits. The Word ‘Computer’ usually refers to the Center Processor Unit plus Internal memory.
  • Charles Babbageis called the “Grand Father” of the computer. The First mechanical computer designed by Charles Babbage was called Analytical Engine. It uses read-only memory in the form of punch cards.


Digital Computer Definition


  • The basic components of a modern digital computer are: Input Device, Output Device, Central Processor Unit (CPU), mass storage device and memory. A Typical modern computer uses LSI Chips.


Four Functions about computer are:


accepts data Input
processes data Processing
produces output Output
stores results Storage


Input (Data):

Input is the raw information entered into a computer from the input devices. It is the collection of letters, numbers, images etc.


Process is the operation of data as per given instruction. It is totally internal process of the computer system.


Output is the processed data given by computer after data processing. Output is also called as Result. We can save these results in the storage devices for the future use.


All general-purpose computers require the following hardware components:

Memory: enables a computer to store, at least temporarily, data and programs.

Mass storage device: allows a computer to permanently retain large amounts of data. Common mass storage devices include solid state drives (SSDs) or disk drives and tape drives.

Input device: usually a keyboard and mouse, the input device is the conduit through which data and instructions enter a computer.

Output device: a display screen, printer, or other device that lets you see what the computer has accomplished.

Central processing unit (CPU): the heart of the computer, this is the component that actually executes instructions.

In addition to these components, many others make it possible for the basic components to work together efficiently. For example, every computer requires a bus that transmits data from one part of the computer to another.

CPU (Processing Unit)

CPU (pronounced as separate letters) is the abbreviation for central processing unit. Sometimes referred to simply as the central processor, but more commonly called processor, the CPU is the brains of the computer where most calculations take place. In terms of computing power, the CPU is the most important element of a computer system.

Components of a CPU

The two typical components of a CPU include the following:

The arithmetic logic unit (ALU), which performs arithmetic and logical operations.

The control unit (CU), which extracts instructions from memoryand decodes and executes them, calling on the ALU when necessary.

Relationship between the elements of the CPU, input and output, and storage

Printed Circuit Boards, Microprocessors

On large machines, the CPU requires one or more printed circuit boards. On personal computers and small workstations, the CPU is housed in a single chip called a microprocessor. Since the 1970’s the microprocessor class of CPUs has almost completely overtaken all other CPU implementations.

The CPU itself is an internal component of the computer. Modern CPUs are small and square and contain multiple metallic connectors or pins on the underside. The CPU is inserted directly into a CPU socket, pin side down, on the motherboard.

Each motherboard will support only a specific type (or range) of CPU, so you must check the motherboard manufacturer’s specifications before attempting to replace or upgrade a CPU in your computer. Modern CPUs also have an attached heat sink and small fan that go directly on top of the CPU to help dissipate heat.





Memory is major part of computers that categories into several types. Memory is best storage part to the computer users to save information, programs and etc, The computer memory offer several kinds of storage media some of them can store data temporarily and some them can store permanently. Memory consists of instructions and the data saved into computer through Central Processing Unit (CPU).

Types of Computer Memory:

Memory is the best essential element of a computer because computer can’t perform simple tasks. The performance of computer mainly based on memory and CPU. Memory is internal storage media of computer that has several names such as majorly categorized into two types, Main memory and Secondary memory.


  1. Primary Memory / Volatile Memory.
  2. Secondary Memory / Non Volatile Memory.


  1. Primary Memory / Volatile Memory:


Primary Memory also called as volatile memory because the memory can’t store the data permanently. Primary memory select any part of memory when user want to save the data in memory but that may not be store permanently on that location. It also has another name i.e. RAM.

Random Access Memory (RAM):

The primary storage is referred to as random access memory (RAM) due to the random selection of memory locations. It performs both read and write operations on memory. If power failures happened in systems during memory access then you will lose your data permanently. So, RAM is volatile memory. RAM categorized into following types.




  1. Secondary Memory / Non Volatile Memory:

Secondary memory is external and permanent memory that is useful to store the external storage media such as floppy disk, magnetic disks, magnetic tapes and etc cache devices. Secondary memory deals with following types of components.

Read Only Memory (ROM) :

ROM is permanent memory location that offer huge types of standards to save data. But it work with read only operation. No data lose happen whenever power failure occur during the ROM memory work in computers.

ROM memory has several models such names are following.

  1. PROM:Programmable Read Only Memory (PROM) maintains large storage media but can’t offer the erase features in ROM. This type of RO maintains PROM chips to write data once and read many. The programs or instructions designed in PROM can’t be erased by other programs.
  2. EPROM :Erasable Programmable Read Only Memory designed for recover the problems of PROM and ROM. Users can delete the data of EPROM thorough pass on ultraviolet light and it erases chip is reprogrammed.
  3. EEPROM:Electrically Erasable Programmable Read Only Memory similar to the EPROM but it uses electrical beam for erase the data of ROM.

Cache Memory: Mina memory less than the access time of CPU so, the performance will decrease through less access time. Speed mismatch will decrease through maintain cache memory. Main memory can store huge amount of data but the cache memory normally kept small and low expensive cost. All types of external media like Magnetic disks, Magnetic drives and etc store in cache memory to provide quick access tools to the users.



Software and application of PC software packages: Software definition, Type of software and its Knowledge of Word processing, Spreadsheets and Power point presentation software packages

Software is a set of programs, which is designed to perform a well-defined function. A program is a sequence of instructions written to solve a particular problem.

There are two types of software −

System Software

Application Software

System Software

The system software is a collection of programs designed to operate, control, and extend the processing capabilities of the computer itself. System software is generally prepared by the computer manufacturers. These software products comprise of programs written in low-level languages, which interact with the hardware at a very basic level. System software serves as the interface between the hardware and the end users.

Some examples of system software are Operating System, Compilers, Interpreter, Assemblers, etc.

Application Software

Application software products are designed to satisfy a particular need of a particular environment. All software applications prepared in the computer lab can come under the category of Application software.

Application software may consist of a single program, such as Microsoft’s notepad for writing and editing a simple text. It may also consist of a collection of programs, often called a software package, which work together to accomplish a task, such as a spreadsheet package.

Examples of Application software are the following −

Payroll Software

Student Record Software

Inventory Management Software

Income Tax Software

Railways Reservation Software

Microsoft Office Suite Software

Microsoft Word

Microsoft Excel

Microsoft PowerPoint


Word Processing, Spread sheet and Power presentation


A word processor is a software program that is used to create a document, store it electronically, display it on a screen, modify it using commands and characters, and print it on a printer. It also processes paragraph indentation, margin size, font type, font size, font color, and spacing within the document being created. Word processors have replaced typewriters since they allow the user to make a change anywhere in the document without having to retype the entire page. Word processors also come equipped with “spell-check” functions eliminating the need for multiple editors and provide an immediate tool for grammatical correction. Some common word processors include Microsoft Word, AbiWord, Word Perfect, and Open Office.

Three basic functions lay the foundation for most of the customization that is needed to create many word documents.

Character Formatting

Character formatting changes the appearance of individual characters and relates to the size, font, color, and overall style of the letters or numbers being used. Character formatting also involves underlining, italicizing, and making bold those characters being used. This is great for making a word stand out or for underlining book titles.

Paragraph Formatting

Paragraph formatting adjusts the spacing, alignment, and indentation of the paragraphs being formed. Spacing refers to the amount of lines left blank in between the lines being processed. A good example of this is double-spacing which is commonly used in an educational setting where a student has to write a paper for a specific instructor. Commonly double-spacing is used so that the instructor can make corrections to the document without having to mark over the actual words on the paper. Alignment refers to the way the paragraph is positioned in regards to the left and right margins. A left alignment is most commonly used when creating a word document and this setting aligns the words being formed to be flush with the left margin. A center alignment is usually used for titling a paper.

Page Formatting

Page formatting refers to the width of the margins, the size of the paper being used, and the orientation of the page. The standard margin is 1.25 inches on both the left and right but these can be customized to suit need and preference. The paper size options reflect what can be used in the printer, and the orientation indicates whether the document will use the traditional or landscape positioning on that paper. Traditional orientation is 8.5 inches wide by 11 inches tall whereas landscape is the exact opposite at 11 inches wide by 8.5 inches tall.



Word processing tools


Some of the basic tools that are employed in word processing programs that help to make the application more user friendly are tables, graphics, and templates. These tools allow for minimal effort and excellent results when adding features like these to a word document.


Tables are used for organizing information and are composed of rows and columns in which data is placed. This is great for comparing and contrasting information as it’s condensed and presented in a straight forward fashion. Tables can also be used for laying out entire documents, such as a resume, where information is sectioned off from one another. In this example, the entire report is formulated to a table instead of a small section as mentioned earlier.


Graphics are pictures, drawings, clip art, or other images that can be inserted into a document from other programs or from stored data on a computer. This makes for easy illustrations where a picture, or pictures, would suffice better than words or tables to highlight a point. Graphics tools also allow the user to manipulate the images that have been imported by changing the color, contrast, brightness, and size of the image, among other things. The customization process of these images in a word processor provide for an easy and quick avenue of explanation concerning the topics at hand.


Another useful tool are Templates. These are preprogrammed arrangements of ideas and/or illustrations that are known to serve a purpose and are already organized for the user to interact with. Most often this means “filling in the blanks” and some common templates that should be recognized are resumes, business cards, identification cards, fax cover sheets, memos, invoices, and newsletters




A spreadsheet is a group of values and other data organized into rows and columns similar to the ruled paper worksheets traditionally used by bookkeepers and accountants.” The spreadsheet software is mandatory to create computerized spreadsheets. Microsoft Excel is a form of a spreadsheet. There are many terms one must have to know to create a spreadsheet. A worksheet is the single spreadsheet document. A workbook allows multiple worksheets to be saved together in a single spreadsheet file. Worksheets are divided into rows and columns. The intersection of a row is called a cell. One must enter content into the active cell, or current cell; it has a border around it to make it be easily identified. Data is entered directly into worksheet cells by clicking a cell to make it the active cell. Labels, constant values, formulas, and functions are the data that is entered into a cell. Before one enters a formula or function into a cell, one must begin with some type of mathematical symbol, usually the equal sign = Spreadsheets are used to organize and calculate data. There is a maximum number of rows and columns in a spreadsheet which varies depending on the version of software you have. It is essential to know how to use spreadsheets for school, work, sports, or anything that requires data!

Tables, graphics, and templates are all available to a user with application software, such as Microsoft Word, Microsoft Excel, and PowerPoint. Tables are ways a user can organize data and information at their convenience. According to Microsoft Word, there are now many different available options for users who are looking for various kinds of tables. These different options include the following: the Graphic Grid, Insert Table, Draw Table, insert a new or existing Excel Spreadsheet table, and Quick Tables. The concept of using tables for data input is relatively simple. In order for a user to insert a table, the user must first open Microsoft Word. Once they have done this, they must click the “table” button to customize the table to achieve their needs. The overall format for a table consists of a large (or small) grid that can be altered by the amount of information the user has, ex. four columns five rows. Next, the user must insert the table into the word document by selecting “insert table” from the dropdown menu. Microsoft Excel contains pivot tables that are tables that include data from a spreadsheet with columns and rows that can be specifically selected.  Graphics in Microsoft Word are pictures, or clip art that are able to be inserted into a Microsoft Word document, Excel Spreadsheet, PowerPoint slide, or any other Office application. the most common graphic used in Excel is graphs. You can create graphs based on data taken from your spreadsheet. Graphics are inserted into these Office Applications to enhance the information presented in a Word Document, Excel worksheet, or PowerPoint slide. A user can insert their own picture through their office documents; add clip art, shapes, SmartArt, screenshot, or Word Art. Templates are pre-constructed document layouts whose primary use is to assist a user in creating a specific type of document in a convenient amount of time. The different options of templates vary, but a few of the following are common ones used every day: agendas, brochures, calendars, flyers, fax covers, and many more. Templates are used to save a user time, and confusion in creating their document.

Using of Spreadsheet


A chart can be created as its own object or embedded within the sheet itself. This is helpful when a user needs to analyze data or represent changing data. Some form of charts are: lines graphs, scatter plot charts, bar charts, Venn diagram charts, and the list goes on.


A function is a pre-programmed mathematical formula to allow the user to make calculations based on the data input. The functions under spreadsheets are there to perform a simple calculation by using a certain value, called arguments.

There are many different reasons to have functions on spreadsheets. One would be for arithmetic functions to process numerical data. The next would be statistical functions that use analysis tools and averaging tools. This would be useful for finding the average of the numbers in a certain row/column on a spreadsheet. The next function is date that processes and converts dates. This function could be used to put the sequential dates in order on the spreadsheet.


A formula identifies the calculation needed to place the result in the cell it is contained within. This means a cell has two display components; the formula itself and the resulting value. Typically, a formula consists of five expressions: value, references, arithmetic operations, relation operations, and functions. By using these expressions, formulas can help to make tables, solve math problems, calculate a mortgage, figure out accounting tasks, and many other business-related tasks that use to be done tediously on paper

Cell Referencing

Cell referencing refers to the ability to utilize a cell or range of cells in a spreadsheet and is commonly used to create formulas to calculate data. Formulas can retrieve data from one cell in the worksheet, different areas of the worksheet, or different cells throughout an entire workbook.


Pivot Tables

One the most powerful features available in the Microsoft Office spreadsheet program Excel, is pivot tables. Pivot tables allow you to manipulate large amounts of raw data. It makes it easy to analyze the data in different ways, with a simple click and drag. Vast quantities of data can be summarized in a variety of ways. Calculations can be performed by row or column. Data can be filtered or sorted automatically by any or all of the fields. Excel can even recommend a basic layout of a pivot table based on the type of data selected.



Powerpoint is a Microsoft Office software used to present information and work as a visual aide. Powerpoint make it easy to organize and present information in a visually appealing way such as charts, pictures, tables, video clips, and sounds. Various Designs and color themes come are built in the software and ready to use. The slides themselves come with several options of pre-loaded layouts, using features such as bullet points, pictures, captions, and titles – These are easy to drag and drop to make rearranging very easy. The idea of a digital visual is to help a presenter engage their audience and display their ideas in a more simple form. One feature that comes in handy is the ability to print the slides so either the presenter or audience can be informed ahead of time of what to expect. Powerpoint also has a notes feature in which you can input notes you may need for your presentation. The notes feature also allows you to print out the notes page with the slide show on it which is known as notes view. You can also adjust the size of the slide on the notes view so that all of your notes fit on the page and looks presentable. If all of your notes do not fit on the notes page provided, it will spill over to the next page. If you know their is a lot of wording, you can make a duplicate slide and hide it in the presentation, so you will have more room for your notes! Teachers, employers, and computer users all over the world have now become accustomed to using PowerPoint as their “go-to” visual aide. The image on the right shows a presenter using a powerpoint as a visual aide.

The PowerPoint presentation graphics program provides the user with several assortment tools and operations for creating and editing slides. With those tools, one is able to add new or delete old slides that are previewed in the slide thumbnail tab area, usually found on the left side of the screen. One is also able to switch to the slide outline tab, which contains only the title and the main text included in the slide. If desired, using the Insert tab, the user can perform additional operations like exporting images, along with adding formatted tables, shapes, symbols, charts, and much more to better express their message. Additionally, to customize the PowerPoint to make it even more dynamic and presentable, text can be animated, and a unique transition can be added to the slides. With animation, text can be set to appear in a specific way in the slide during a slide show. Tons of special effects are provided for the user, including animations to make the text to fly, dissolve, fly, float, or bounce in. Similarly, one is also able to apply special effects to specific slides to transition from one slide to another in a specific manner. Additionally, Microsoft PowerPoint allows recorded narration to be played back as the slideshow is being presented, along with speaker notes. Furthermore, most presentation graphics programs also allow the user to print those speaker notes for the targeted audience’s convenience.



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