Development of Computers

Development of Computers The earliest known device to record computations was the abacus. It dates back to ancient times and was invented by the Chinese. Ten beads were strung onto wires attached to a frame. Addition and subtraction were read from the final positions of the beads. It was considered the first manual tool used in calculating answers to problems that provided information and in a primitive way storing the results. Abacus Mechanical Clock During the Middle Ages the first closed system in terms of calculating information was invented by use of a mechanical clock. The parts of the clock calculated the time of day. The time was displayed through the position of two hands on its face. The inventor pre-programmed the clock instructions through the manner in which the pull of the weights and the swing of the pendulum with the movement of the gears established the position of the hands on the clock face. Mathematics John Napier (Scotsman mid 1600s) discovered logarith

Computer software

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Computer software 

Computer software, or just software, is a collection of computer programs and related data that provides the instructions for telling a computer what to do and how to do it.


How users communicate with computers:

A layer structure showing where the operating system software and application software are situated while running on a typical desktop computer

Classification of computer software


Software can be classified as shown in the organizational chart below:

Classification according to purpose

Software can be classified in regard to what they are used for. i.e. system software and application software

System Software

System software is a program that manages and supports the computer resources and operations of a computer system while it executes various tasks such as processing data and information, controlling hardware components, and allowing users to use application software. That is, systems software functions as a bridge between computer system hardware and the application software.

Three Kinds of System Software

Systems software consists of three kinds of programs. The system management programs, system support programs, and system development programs are they. These are explained briefly.

1.     System Management Programs

These are programs that manage the application software, computer hardware, and data resources of the computer system. These programs include operating systems, operating environment programs, database management programs, and telecommunications monitor programs. Among these, the most important system management programs are operating systems.

2.     System Support Programs

These are the programs that help the operations and management of a computer system. They provide a variety of support services to let the computer hardware and other system programs run efficiently. The major system support programs are system utility programs, system performance monitor programs, and system security monitor programs (virus checking programs).

3.     System Development Programs

These are programs that help users develop information system programs and prepare user programs for computer processing. These programs may analyze and design systems and program itself. The main system development programs are programming language translators, programming environment programs, computer-aided software engineering packages.

Operating Systems

An operating system is a collection of integrated computer programs that provide recurring services to other programs or to the user of a computer. These services consist of disk and file management, memory management, and device management. In other words, it manages CPU operations, input/output activities, storage resources, diverse support services, and controls various devices.
Operating system is the most important program for computer system. Without an operating system, every computer program would have to contain instructions telling the hardware each step the hardware should take to do its job, such as storing a file on a disk. Because the operating system contains these instructions, any program can call on the operating system when a service is needed. Examples include:
DOS - Disk Operating System - one of the first operating systems for the personal computer. When you turned the computer on all you saw was the command prompt which looked like c:\ >. You had to type all commands at the command prompt which might look like c:\>wp\wp.exe. This is called a command-line interface.
It was not very "user friendly"
  • Windows - The Windows operating system, a product of Microsoft, is a GUI (graphical user interface) operating system. This type of "user friendly" operating system is said to have WIMP features:
    • Windows
    • Icons
    • Menus
    • Pointing device (mouse)
  • Mac/OS - Macintosh, a product of Apple, has its own operating system with a GUI and WIMP features.
  • UNIX - Linux (the PC version of UNIX) - UNIX and Linux were originally created with a command-line interface, but recently have added GUI enhancements.

Firmware /stored logic

This is the combination of persistent memory and program code and data stored permanently on electronic chips. The firmware contained in these devices provides the control program for the device. Firmware is held in non-volatile memory devices such as ROM, EPROM, or flash memory. They hold operating systems, utility programs, language processors etc.

Utility software

Utility software is designed to help analyze, configure, optimize or maintain a computer. A single piece of utility software is usually called a utility or tool. Utility software usually focuses on how the computer infrastructure (including the computer hardware, operating system, data storage and application software operates)

Utility software categories

  • Anti-virus utilities scan for computer viruses.
  • Archive utilities output a stream or a single file when provided with a directory or a set of files.
  • Backup utilities can make a copy of all information stored on a disk, and restore either the entire disk (e.g. in an event of disk failure) or selected files (e.g. in an event of accidental deletion).
  • Cryptographic utilities encrypt and decrypt streams and files.
  • Data compression utilities output a shorter stream or a smaller file when provided with a stream or file.
  • Data synchronization utilities establish consistency among data from a source to target data storage and vice versa. There are several branches of this type of utility:
    • File synchronization utilities maintain consistency between two sources. They may be used to create redundancy or backup copies but are also used to help users carry their digital music, photos and video in their mobile devices.
    • Revision control utilities are intended to deal with situations where more than one user attempts to simultaneously modify the same file.
  • Disk checkers can scan operating hard drive.
  • Disk cleaners can find files that are unnecessary to computer operation, or take up considerable amounts of space. Disk cleaner helps the user to decide what to delete when their hard disk is full.
  • Disk compression utilities can transparently compress/uncompress the contents of a disk, increasing the capacity of the disk.
  • Disk defragmenters can detect computer files whose contents are broken across several locations on the hard disk, and move the fragments to one location to increase efficiency.
  • Disk partitions can divide an individual drive into multiple logical drives, each with its own file system which can be mounted by the operating system and treated as an individual drive.
  • Disk space analyzers for the visualization of disk space usage by getting the size for each folder (including sub folders) & files in folder or drive. Showing the distribution of the used space.
  • Disk storage utilities
  • File managers provide a convenient method of performing routine data management tasks, such as deleting, renaming, cataloging, un-cataloging, moving, copying, merging, generating and modifying data sets.
  • Hex editors directly modify the text or data of a file. These files could be data or an actual program.
  • Memory testers check for memory failures.
  • Network utilities analyze the computer's network connectivity, configure network settings, check data transfer or log events.
  • Registry cleaners clean and optimize the Windows registry by removing old registry keys that are no longer in use.
  • Screensavers were desired to prevent phosphor burn-in on CRT and plasma computer monitors by blanking the screen or filling it with moving images or patterns when the computer is not in use. Contemporary screensavers are used primarily for entertainment or security.
  • System monitors for monitoring resources and performance in a computer system.
  • System profilers provide detailed information about the software installed and hardware attached to the computer.

Networking software

 This software is used to establish communication between two or more computers by linking them using a communication channel like cables to create a computer network. It enables the exchange of data in a network as well as providing data security. Networking software may come as independent software or integrated in an operating system. Examples include: novel Netware, windows NT etc.
When computers communicate to one another, they need networking software often referred to as a protocol. A protocol is a set of rules that govern how data packets move from one computer to another on a network connection.

Application software

This is computer software designed to help the user perform a specific task. Examples include enterprise software, accounting software, office suites, graphics software and media players. This book will mostly feature office suites.

Office suites

Existing office suites contain wide range of various components. Most typically, the base components include:
  • Word processor-allows users to create edit and save documents. Examples: Ms Word, open, lotus word pro, word pad, libreoffice writer etc.
  • Spreadsheet- allows users to create documents and perform calculations. Examples: Ms Excel, Lotus 1-2-3, open, VisiCalc etc.
  • Computer Aided Design- is the use of computer systems to assist in the creation, modification, analysis, or optimization of a design or he process of creating a technical drawing with the use of computer software. It can also be classified as a vector graphic under graphics suite. Example: AutoCAD, PLaSM, NCLab etc.
  • Presentation program-allows users to create visual presentations. Example: Ms Power Point, Corel Presentations, Google Docs etc.
  • Database-allows users to store and retrieve vast amount of data. Example: Ms Access, MySQL, Oracle etc.
  • Graphics suite (raster graphics editor, vector graphics editor, image viewer- allows users to manipulate visual images on a computer. Example: Corel Draw, Photoshop, Graphic Art, Xnview, Picasa, Ms Movie maker etc.
  • Desktop publishing software-allows users to create printed materials using page layout on a personal computer. Example: Ms Publisher, Adobe PageMaker,    Adobe InDesign, Corel Ventura, Adobe FrameMaker etc.
  • Formula editor- allows users to typeset mathematical works or formulae. Example: Aurora, Ms Equation Editor, MathMagic, EqualX etc.
  • Email client-allows users to access and manage their Email accounts. Example: GNUmail, Opera mail, Ms Outlook, Apple mail etc.
  • Web browsers- used for retrieving, presenting, and traversing information resources on the World Wide Web. Examples: Firefox, Opera, Google Chrome, Safari, Internet explorer etc.
  • Personal information manager (PIM)- used to organize personal information. a PIM tool's purpose is to facilitate the recording, tracking, and management of certain types of "personal information". Example: Windows calendar, windows contacts, Chandler, OpenIRIS etc.

Classification according to acquisition


In-house developed software

These are programs designed to meet a specific user’s needs. In this situation, a system analyst studies an existing system (most likely manual) and together with a programmer, they make a new computerized system to fit the needs of their client. For example, a school can hire a computer analyst to design a program that can be used to produce report cards.

Vendor off-the-shelf software

This kind of software is developed by software engineers, packaged and then made available for purchase through a vendor, a distributor or directly from the developer. Several applications may be bundled together to form a suite e.g. Microsoft office, Lotus suite, Corel word perfect, quick books etc.
Advantages of standard software over in-house developed programs are:
1.      They can easily be installed and run.
2.      They are cheaper.
3.      They can do a variety of tasks
4.      They are reliable because they have minor errors in them.
5.      They can easily be modified or customized to fit user needs.
6.      They are compatible to a large variety of computer hardware

Disadvantages of Off-the-Shelf software (standard)

  1. Are expensive
  2. Not compatible to a variety of hardware setup
  3. Require large computer memories to run
  4. Require extra training from basic training
  5. Prone to errors
  6. Have a limited number of controls therefore not so user friendly.

Advantages of off –the- shelf software

  1. Solve specific problems that cannot be dealt by standard software.
  2. Address inner details of a task.
  3. Users are involved when designing the software. Therefore the requirements are clearly addressed.
  4. More creativity is enhanced by the programmer to make his/her product marketable.

Classification according to End-User-License:

This is software that is available for use at no cost or for an optional fee, but usually with one or more restricted usage rights.
Example: Adobe reader, Adobe flash player, Ubuntu operating system, Rising Antivirus, VLC media player etc. This software is sourced for free but they are vulnerable to computer viruses or can carry a virus unto your computer.
Shareware (also termed trialware or demoware) is proprietary software that is provided to users without payment on a trial basis and is often limited by any combination of functionality, availability (it may be functional for a limited time period only), or convenience (the software may present a dialog at startup or during usage, reminding the user to purchase it; "nagging dialogs"). Shareware is often offered as a download from an Internet website or as a compact disc included with a periodical such as a newspaper or magazine. The rationale behind shareware is to give buyers the opportunity to use the program and judge its usefulness before purchasing a license for the full version of the software. Firms with superior software thus have an incentive to offer samples, except if their product is already well known, or if they do not want to be listed in direct competition with other products on shareware repositories.
Proprietary software is computer software licensed under exclusive legal right of the copyright holder. The licensee is given the right to use the software under certain conditions, while restricted from other uses, such as modification, further distribution, or reverse engineering.
Free and open-source software (FOSS) or free/libre/open-source software (FLOSS) is software that is both free software and open source. It is liberally licensed to grant users the right to use, copy, study, change, and improve its design through the availability of its source code. This approach has gained both momentum and acceptance as the potential benefits have been increasingly recognized by both individuals and corporations.
Open-source software (OSS) is computer software that is available in source code form: the source code and certain other rights normally reserved for copyright holders are provided under an open-source license that permits users to study, change, improve and at times also to distribute the software. Example: Linux
Criteria for selecting a computer system
When purchasing a computer hardware or software, consider a number of requirements necessary to fit your needs and costs.

Hardware considerations

  1. Microprocessor type and speed- the speed and processing power of a computer depends on the type of CPU and its clock speed. Consider microprocessors with high cache memory and faster clock speeds since they can be able to run a variety of tasks without strain. Intel Duo Core and AMD Duron are the latest for PCs.
  2. Memory capacity- Consider the capacity of your memory since higher memories creates good performance of your computer. Check whether it’s static or dynamic, DDR or SDR, empty memory slots on the motherboard and whether they are up gradable with other installed modules.
  3. Warranty- A warranty is an agreement between the buyer and the seller that spells terms and conditions of, after selling a product incase of failure or malfunction.
A good warranty should cover the following:
a)      Scope of cover i.e. one year
b)      Callout response and liability agreement
c)      Preventive performance.
  1. Cost- The cost of a computer system depends on:
a)      Processing power
b)      Whether it’s a Branded or a clone- a clone is a hardware or software system that is designed to mimic another system whilst a branded computer is a computer whose parts are made by one company copyrighted and standardized, they are more expensive than clones but are of high quality. Examples: Dell, Acer, Compaq, HP, Apple etc.
c)      Size- Portable computers are more expensive than desktops because of the complexity of technology used to make them.
  1. Upgradeability and Compatibility- Upgradeability is the ability of a system to embrace to new forms of technology available in the market and Compatibility is the ability of a system to run in more than one different system families. For example: a computer that can run on windows, MAC, Ubuntu, etc operating systems.
  2. Portability- Consider your user needs and decide whether you need a computer that you can easily carry from one place to another or fixed in one place. In this case, a palmtop or a laptop and a desktop are convenient respectively.
  3. User Needs- Value your user needs and any other needs you will use this computer for. If you want a variety of tasks, then try a general purpose computer.
  4. Monitors- Check for video adaptors, resolution, power consumption and saving, technology used to manufacture them (TFT, Gas Plasma, CRT etc)
  5. Multimedia Capabilities – This is the ability to support multimedia functions like: sound card, TV card, SVGA monitor, CD/DVD drives etc.
  6. Cabling- check whether the ports are user friendly, wireless or bound and strategically positioned on the system unit which might be a tower or a desktop type.

Software considerations

  1. Authenticity –this is the genuineness, validity and legitimacy of an item.
  2. Documentation- Availability of user manuals prepared by the developer with details on how to install, use and maintain the software. i.e. installation guide, maintenance guide and a user guide.
  3. User needs- User needs dictates the type of software to purchase. For example: if the user wants to type letters, memos, CVs etc. the word processors are valid.
  4. Portability- This is the ability of the acquired software to be installed in more than one family of computer hardware. For example: if it can accept MAC computers, 32-bit, 64-bit computers etc.
  5. Compatibility and system configuration- A software product should be compatible with the existing hardware, operating system or application programs and should be readily upgradeable.
  6. User friendliness- this is the measure of how easily the users can be able to operate the computer. User friendly software should have WIMP- Windows Icons Menus and Pointing devices.
  7. Cost- Consider cost effective software. I.e. the benefits should outweigh the costs.

Operating systems (OS)

An operating system (OS) is a collection of software that manages computer hardware resources and provides common services for computer programs. The operating system is a vital component of the system software in a computer system. Application programs require an operating system to function.

How the operating system works

How the operating system works

For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware, although the application code is usually executed directly by the hardware and will frequently make a system call to an OS function or be interrupted by it. Operating systems can be found on almost any device that contains a computer—from cellular phones and video game consoles to supercomputers and web servers.

Operating system types


Operating system types
As computers have progressed and developed so have the operating systems. Below is a basic list of the different operating systems and a few examples of operating systems that fall into each of the categories. Many computer operating systems will fall into more than one of the below categories.
Single program OS-also known as single tasking OS allows processing of one application program in the main memory at a time. Below are some examples of single program operating systems.
-Ms Dos
Multitasking - An operating system that is capable of allowing multiple software processes to run at the same time. Below are some examples of multitasking operating systems.
Windows 2000
Single user OS- is designed for use by only one person. Below are some examples of single user operating systems.
-Ms Dos
Multi-user - A multi-user operating system allows for multiple users to use the same computer at the same time and different times. Below are some examples of multi-user operating systems.
-Windows 2000
Multiprocessing - An operating system capable of supporting and utilizing more than one computer processor. Below are some examples of multiprocessing operating systems.
-Windows 2000
Multithreading - Operating systems that allow different parts of software program to run concurrently. Operating systems that would fall into this category are:
Windows 2000
GUI - Short for Graphical User Interface, a GUI Operating System contains graphics and icons and is commonly navigated by using a computer mouse. Below are some examples of GUI Operating Systems.
-System 7.x
-Windows 98, XP, Vista
-Windows CE
Menu-driven- provides the user with a list of options to choose from. Example: Dos shell/Dos editor
Command-line- lets the user type command at a prompt. The computer reads the typed command from the command line and executes it. Example: Ms Dos

Functions of operating systems in resource management

The major functions of an OS are:
  1. Processor Scheduling- The operating system allocates each job waiting for execution, processor time at each give interval. The OS schedules jobs according to priorities.
  2. Resource allocation- Each available resource is given a unique identification number called an interrupt request (IRQ). The OS uses the IRQ number to identify the resources being requested. Poor resource allocation would result to an undesirable condition referred to as deadlock. Deadlock is a situation which occurs when a process enters a waiting state because a resource requested by it is being held by another waiting process, which in turn is waiting for another resource.
  3. Memory management- The operating  system determines which task remains can be held by the memory and which one can be suspended to the secondary storage devices , output and to the processor.
  4. Input/Output management –The OS coordinates between various I/O (input/output) and other peripheral devices such as auxiliary storage devices, making sure that data is transmitted securely.
  5. Communication control and management- This involves management of various communication devices and providing an environment within which communication channels operate.
  6. Error handling- The OS has many ways of alerting the user of errors that may arise out of illegal operations, hardware or software failure. Most OS express what the error is, and where possible make suggestions on how to correct the error.
  7. Process management
-all processes from start to shut down
-booting, open, save, install, copy, print
  1. File management- this involves naming of file and folders, locations, attributes (size, type, modified, protection, password etc.
  2. Security management-this involves Virus management, Alert messages, Dialogue boxes, Firewall, passwords/Access protection etc.
  3. Interrupt handling- An interrupt is a break from the normal sequential processing of instructions in a program. A critical request causes the processor to stop executing the current process to attend to it, before returning the control back to the process that was initially interrupted.

Typical Day-to-Day Uses of an Operating System:

-Executing application programs.
-Formatting floppy diskettes.
-Setting up directories to organize your files.
-Displaying a list of files stored on a particular disk.
-Verifying that there is enough room on a disk to save a file.
-Protecting and backing up your files by copying them to other disks for safekeeping.

Factors to consider when choosing an operating system:

When choosing and operating system, similar factors as those of choosing software can be considered as listed below:
  1. Hardware configuration i.e. speed, capacity, memory etc.
  2. Make, size and nature of the computer i.e. laptop, desktop, phone, mainframe etc
  3. Application software intended for the computer
  4. User-friendliness
  5. Documentation
  6. Cost
  7. Reliability and security
  8. Number of processors and hardware available
  9. Number of users.
  10. upgradeability

How an operating system organizes information

Operating systems store information almost in a similar way. OS manufacturers consider a number of factors when designing an OS which is user friendly. This includes:
  1. Rapid access: this method allows quick access to stored data.
  2. Ease of update: the organization should allow quick and easy updating of files
  3. Keep track of changes: the organization should be able to keep track of change as they unfold. I.e. date, size, format, type etc.
  4. Reliability: the organization should be relied upon by maintaining higher standards of data integrity.
  5. Economy of storage: the organization should be able to utilize the available storage.
  6. Simplicity of maintenance: the organization method should enable quick navigation through the file system and make it easy to maintain.

How the OS organizes information in drives, folders/directories and files


Hierarchical organization of drives, folders and files

Drives- a drive is a general term used to refer to any device that can be used to write/read disk storage of any category i.e. floppy drive, CD drive, Hard disk drive etc. To differentiate from one drive to another, the OS system assigns each drive a unique letter and icon as shown in the diagram below.

Assigning of letters by the OS

Drive letter assignment is the process of assigning alphabetical identifiers to physical or logical disk drives or partitions (drive volumes) in the root file system namespace; this usage is now mostly found in Microsoft operating systems.
 Most OS assign letters according to the number of available drives in your computer. Example:
  • A: — Floppy disk drives, 3.5" or 5.25", and possibly other types of disk drives, if present.
  • B: — Reserved for a second floppy drive, if present.
  • C: — First hard disk partition.
  • D: to Z: — other disk partitions get labeled here. The letter D: or E: are often assigned to CD-ROM, DVD drives but not always. In fact, Windows assigns the next free drive letter to the next drive it encounters while enumerating the disk drives on the system during installation. Drives can be partitioned, thereby creating more drive letters. This applies to MS-DOS, as well as all Windows operating systems. Windows offers other ways to change the drive letters, either through the Disk Manager (Windows NT, 2000, XP and later) or through the Device Manager found in the Control Panel. MS-DOS typically uses parameters on the line loading device drivers inside the CONFIG.SYS file.
  • F: — first network drive if using Novell NetWare.
  • H: — "Home" directory on a network server.



a directory, also referred to as a folder, catalog or drawer, is a virtual container within a digital file system, in which groups of computer files and possibly other directories can be kept and organized. The technically correct name for such a file cataloging structure is directory, although names such as folder and drawer were adopted to provide some relevancy to the traditional office file cabinet.
Files are kept organized by storing related files in the same directory. In a hierarchical filesystem (that is, one in which files and directories are organized in a manner that resembles an inverted tree), a directory contained inside another directory is called a subdirectory. The terms parent and child are often used to describe the relationship between a subdirectory and the directory in which it is cataloged, the latter being the parent. The top-most directory in such a filesystem, which does not have a parent of its own, is called the root directory.

Shortcut folders

            This is a link to the original folder for quicker access. Most of these links are available on the desktop. These links don’t have contents of their own and therefore should not be created on a removable media (most people loss data in this way). To identify the link, check for an arrow for the shortcut folder as shown below
To create a new folder
  1. Open My Documents.
  2. Under File and Folder Tasks, click Make a new folder.
A new folder is displayed with the default name, New Folder, selected.
  1. Type a name for the new folder, and then press ENTER.
To make a shortcut in a folder
 Open My Documents.
If the folder where you want to place the shortcut is not located in My Documents or its subfolders, use Search to find it. To open Search, click Start, and then click Search.
  1. Double-click the folder where you want to place the shortcut.
  2. On the File menu, point to New, and then click Shortcut.
  3. Follow the instructions in the Create Shortcut Wizard.

Compressed (zipped) Folders overview

Folders that are compressed using the Compressed (zipped) Folders feature use less drive space and can be transferred to other computers more quickly. You can work with a compressed folder and the files or programs it contains just as you would an uncompressed folder.
Once you have created a compressed folder (identified by the zipper on the folder icon), you can compress files, programs, or other folders by dragging them to it. You can open files directly from compressed folders, or you can extract files before opening them.
You can run some programs directly from zipped compressed folders, without decompressing them. However, to run programs that are dependent on other files, you must first extract them.
Compressed folders can be moved to any drive or folder on your computer. You can also share zipped compressed folders with other users, even if they use a different file compression program.
You can protect zipped compressed folders with a password. This protects your data if you save it in a shared network folder, attach it to an e-mail message, or move it between work and home on floppy disks.
To create a zipped compressed folder
  1. Open My Computer.
  2. Double-click a drive or folder.
  3. On the File menu, point to New, and then click Compressed (zipped) Folder.
  4. Type a name for the new folder, and then press ENTER.

Moving and Files/Folders

You can move your files and folders in Windows XP. Moving a file or an entire folder (including its contents) allows you to organize your files better or create a more logical structure of files to navigate through. Windows XP makes it a simple process to move files or folders to a different location.
  1. Open My Documents.
If the file or folder you want to move is not located in My Documents or its subfolders, use Search to find it. To open Search, click Start, and then click Search.
  1. Click the file or folder you want to move.
  2. Under File and Folder Tasks, click Move this file or Move this folder.
  3. In Move Items, click the new location for the file or folder, and then click Move.

Copying files and Folders

When you copy a file or folder, you are making a duplicate of the original item that you can then modify, delete, or store independently of the original.
1.      Open the location that contains the file or folder you want to copy.
2.      Right-click the file or folder you want to copy, and then click Copy.
3.      Open the location where you want to store the copy.
4.      Right-click within the location, and then click Paste.
The copy of the original file or folder appears in the new location.


A computer file is a resource for storing information, which is available to a computer program and is usually based on some kind of durable storage or a computer file, can be described as a collection of data or information that has a name, called the filename. Almost all information stored in a computer must be in a file. There are many different types of files: data files, text files, program files, directory files, and so on. Different types of files store different types of information. For example, program files store programs, whereas text files store text.
Computer file types can be characterized in a few major groups:
  • System File - is a computer file important to the operating system.
  • Application File –hold programs and are executable  
  • Data Files – contain user’s specific data.
Every file has the following details:
  1. Size, date, and time the file was created or modified
  2. A unique name and an optional extension. The name and extension are separated by a period (.) e.g. filename.exe.
To see details of any file, proceed as follows:
*      Right click on file icon and choose properties
*      Click the general tab to see properties
The table below shows a match between programs and extensions.

Computer File Types by Extension

file extensions

Renaming files and folders

This means giving a folder a new name from the previous.
To rename, proceed as follows:
  1. Select the files/folders you want to rename.
  2. On the File menu, click Rename.
  3. Type the new name, and then press ENTER.

Deleting files and folders

Deleting is getting rid of a file/folder in their current storage location. Deleted files/folders never disappear completely but are temporarily placed in the recycle bin to avoid permanent disappearance of a file/folder if it was deleted by mistake.
To delete a file, proceed as follows:
  1. Click the file or folder you want to delete.
2.      Under File and Folder Tasks, click Delete this file or Delete this folder.
*      You can also delete files or folders by right-clicking the file or folder and then clicking Delete.
*      To retrieve a file you have deleted, double-click the Recycle Bin icon on your desktop. Right-click the file you want to retrieve, and then click Restore.
*      To permanently delete a file, press and hold down SHIFT and drag it to the Recycle Bin. The item is permanently deleted and cannot be retrieved from the Recycle Bin.

Sorting files/folders

Sorting is arranging files/folders in a particular order i.e. alphabetically, by date, modification date, type and size.
Windows provides several new ways for you to arrange and identify your files when viewing them in folders, such as My Documents. When a folder is open, you can access each of the following view options on the View menu.

Show in Groups

Show in Groups allows you to group your files by any detail of the file, such as name, size, type, or date modified. For example, if you group by file type, image files appear in one group, Microsoft Word files appear in another group, and Excel files in another. Show in Groups is available in the Thumbnails, Tiles, Icons, and Details views. To show your files in groups, on the View menu, point to Arrange Icons by, and then click Show in Groups.
Thumbnails view displays the images a folder contains on a folder icon so you can quickly identify the contents of the folder. For example, if you store pictures in several different folders, in Thumbnails view, you can tell at a glance which folder contains the pictures you want. Windows displays up to four images on a folder background, by default. Or, you can choose one picture to identify a folder in Thumbnails view. The complete folder name is displayed under the thumbnail.
Tiles view displays your files and folders as icons. The icons are larger than those in Icon view, and the sort information you select is displayed under the file or folder name. For example, if you sort your files by type, "Microsoft Word document" appears under the file name for a Microsoft Word document.

Filmstrip view is available in picture folders. Your pictures appear in a single row of thumbnail images. You can scroll through your pictures using the left and right arrow buttons. If you click a picture, it is displayed as a larger image above the other pictures. To edit, print, or save the image to another folder, double-click the picture.
Icons view displays your files and folders as icons. The file name is displayed under the icon; however, sort information is not displayed. In this view you can display your files and folders in groups.
List view displays the contents of a folder as a list of file or folder names preceded by small icons. This view is useful if your folder contains many files and you want to scan the list for a file name. You can sort your files and folders in this view; however, you cannot display your files in groups.
In Details view, Windows lists the contents of the open folder and provides detailed information about your files, including name, type, size, and date modified. In Details view you can also show your files in groups.
To choose the details you want to display, on the View menu, click Choose Details.

Selecting files/folders

Selecting is highlighting files/folders for manipulation.
    • To select consecutive files or folders, click the first item, press and hold down SHIFT, and then click the last item.
    • To select nonconsecutive files or folders, press and hold down CTRL, and then click each item.
    • To select all the files and folders in the window, on the Edit menu, click Select All.
-If you have selected all files or folders and then want to clear the selection, click in a blank area in the folder window.

Refresh command

To refresh means to reload a window for better performance or to update displayed information with current data.
To refresh:
  1. right click on a blank area in a folder or desktop window
  2. on the dropdown menu that appears click refresh command

Recycle Bin

This is the place in which Windows stores deleted files. You can retrieve files you deleted in error, or you can empty the Recycle Bin to create more disk space.



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