Fundamental Concepts Of Computer System - Kmacims | Education Annex (2023)

Basic Concepts of Computer

Fundamental concepts of computer system beginners should learn are discussed here. At the end of this module, students should be able to define a computer; define a computer as Input Process Output (IPO); describe parts of a computer system; list the input devices, output devices and components of a system unit.

Definition of a Computer

A computer is an electrical appliance that performs predetermined tasks. A computer system is a group of distinct objects that work together to perform a task. It can equally be defined as an IPO (Input Process Output system) as follow: a set of electronic appliance that accepts (input), processes (processing), stores (Storage), outputs (output) and communicates information based on a predetermined program. This definition differentiates four basic functions of a Standalone computer as Input, Processing, Storage and Output; and five functions of a Network computer as Input, Output, Storage, Processing, and Communication.

The IPO Diagram

A Standalone computer is a computer systemthat is not connected to another computer, while a Network computer isa computer that is connected (networked) to another computer through wired orwireless means to enable the communication function (information exchange) of acomputer system.

Parts of a Computer System

A functional computer system has but is not limited to the following parts: System unit, monitor or Visual Display Unit (VDU), keyboard, mouse, printer, speakers, power and other connecting cables, Uninterruptible Power Supply (UPS), scanner, microphone, and joystick. These parts of a basic computer system are divided into two: main and peripheral parts. The main devices include a system unit, monitor, mouse, and keyboard. These components are essential for smooth booting, and use of a typical computer system. The peripherals parts include a printer, speaker, scanner, digital camera, light pen, and so on. A computer can be used without the peripheral devices, however, certain support provided by the peripherals are not possible if they are not present. Thus, a computer without a printer will not be able to print out a document. The figure below shows the parts of a computer system.

The parts of the computer enlisted above can be divided intoinput and output devices. Input devices includea keyboard, mouse, scanner, light pen,joystick, digital camera, and a microphone. Input is the process of sendingdata into the processing section of the computer. Various forms of data can bepassed into the computer including text, sound, image, and video. These dataforms are sent into the system using input devices. Output devices include a monitor(VDU), printer and speaker.

All the components of a computer system are connected to thesystem unit. The system unit is made up of hidden components that should not beeasily touched by the ordinary user. Someof the components inside the system unit arehard disk drive (HDD), RAM (memory), Central Processing Unit (CPU), cooling fanand heat sink, Power Park, CD/DVD drive, floppy disk drive, and motherboard.

The processing devices include the CPU (microprocessor) andthe memory unit; both located inside the system unit.

The table below shows the basic parts of a computer system and its functions.

The Following are the Images of the above tabulated components

Input Devices

Input is the process of sending data into the processingsection of the computer.

The Keyboard

This is a small board with several alphabetic and numeric keys like a typewriter. It is flat and easy to carry. The keyboard has 102 or 105 keys mounted on soft springs such that when a key is pressed, a text is inserted in an open text document; pressing a key may also cause the command to be executed. Each key is labeled on the top with one or more symbols. The keys on the keyboard are grouped into four namely:

1. Function Keys: F1, F2 … F12
2. Alphabetical Keys: Aa, Bb, …, Zz
3. Numeric Keys: 0, 1, 2, …, 9
4. Special Keys: “, >, @, Tab, Caps lock, Ctrl,Alt, Esc, Shift, …

Use of Various Keys

ALPHABETIC KEYS: These keys appear at the center of the keyboard and have the following arrangement as observed in a typical typewriter.

If you want to type ‘Genesis’, you simply need to press therespective keys in the following order: ‘G’, followed by ‘E’, followed by ‘N’,‘E’, ‘S’, ‘I’, ‘S’. Also, pressing ‘;’, ‘,’ and ‘.’ keys would produce a semicolon, comma, and full stop respectively.

NUMERIC KEYS: Thenumeric keys are used to type decimal digits or numbers into the computersystem. You can either use the keys labeled1, 2, …, 0 or use the numeric keypad.Before using the numeric keypad, you must turn on the Num Lock key. To turn on the num lock key, press the num lock key at the numeric keypad andwatch to see if the num lock light is on.

FUNCTION KEYS:Across the top of the keyboard is a line of function keys labeled F1, F2, …, F12. These keys can be customized to perform varying functions indifferent applications. For example, F5 is used to execute a T-SQL query in MSSQL Server and used to start a slideshowin MS PowerPoint, it is also used to test/run program instructions in Visualbasic application development environment. F1 is used in most applications to displaythe help window. Also, the function keys can be used together with the Ctrl,Alt, and Shift keys to execute predefined commands.

SPECIAL KEYS: Thelist of special keys includes Esc, Tab, Caps Lock, Shift, Ctrl, Alt,Enter/Return, Backspace and Delete. These keys modify the effect of thealphabetic keys, control the cursor and are used together with other keys toexecute predefined commands. The individual functions of these keys are furtherexplained below.

Esc: Esc key is used to cancel the operation or used to terminate a running command.

Caps Lock: It is used to produce an uppercase letter when it isturned on. When it is turned off it will produce a lowercase letter.

Tab: The tab can be used in tab selection or in positioning thecursor in a text application window.

Shift: Holding down the shift key and typing any alphabet produces an uppercase letter if the caps lock key is off and lowercase letter if the caps lock key is on. Also, holding the shift key and pressing any of the keys that has two symbols on it would insert the upper symbol in the document. For example, to type parenthesis, hold the shift key and press ‘9’ and ‘0’ and so on. The shift key can also be used in combination with other special keys to execute commands in the different application environment.

Ctrl: It can be used in combination with other keys to execute specificcommands depending on the application environment. E.g., in a word document, holdingthe Ctrl key and pressing F4 (Ctrl + F4) will close a window.

Alt: It can be used in combination with other keys to executepredefined commands. For example, Alt +F opens the file menu list, Alt+F4 exitsan application window.

Enter/Return: This is the most important key on the keyboardbecause it is mostly used. It is used to execute a command, especially, in thecommand environment. When typing in a word document, you use it to move downthe line row-wise or create a paragraph.

Backspace: It is used to erase typed texts backward, i.e. erasingtexts leftward to the left of the cursor.

Delete: Is used to erase forward texts or texts rightward ofthe cursor. It is also used to delete files and folders in windows explorer.

Spacebar: Is used tocreate space in between words.

Cursor control keys – the four arrow keys in between the QWERTYkeys and the numeric keypad. The left arrow (←) moves cursor backward; rightarrow (→) moves the cursor forward; uparrow (↑) moves cursor upward and down arrow (↓) moves the cursor downward. Page up moves cursor upward page-wise, Page down moves cursor downwardpage-wise. Home takes the cursor tothe beginning of the line or beginning of a sentence. End takes the cursor to the end of a line or sentence.

The cursor is a black line (|) that blinks like anautomobile traffic light when a text document is opened. Its position tells youwhere the next input will appear or be inserted.

The Mouse

This is a small handy box that looks like a mouse. It is actually a box of electronics and mechanics with pointing and picking a device. There are two kinds: the Ball roll mouse and the Optical mouse. The rolling of the ball is tracked by an image called mouse pointer. The mouse is used in signaling and selection. You can use the mouse to select items of your choice in a list of items known as a menu by clicking on the choice item or from a list of icons on the desktop.

To select an item, the user simply clicks on the item bypressing the left mouse button. You can use the right mouse button to display amenu for the selected item by simply pressing the right mouse button.

When the right mouse button is pressed (right-clicking) on an icon or an object or anempty space, by default, a pop-up menu from where you can select an itemappears.

Differences between the Keyboard and Mouse

1. The main purpose of a mouse is to guide thecursor on the computer monitor, while a keyboard is a typewriter-like device withsome additional functions that allow human interaction with the computer.
2. The keyboard is the only source of providingtext input to the computer. Mouse and keyboard are user interface that allowshuman interaction with a computer.
3. While a mouse is used as a pointing devicecontrolling the cursor, a keyboard is input device used to provide inputcommands and to type in word processors and text editors.
4. The keyboard has keys labeled 1, 2, …, A, B, … Z while the mouse has buttons.
5. A standard keyboard has 102 or 105 keys whilemouse has 2 buttons and a knob.

Output Devices

Output is the process of retrieving processed data from thecomputer and presenting them in a human-readableform. The various forms of information that can be retrieved from the computer include text, sound, and visual images. Thesedata forms can be produced using the following devices: printer, monitor, andspeaker.

Monitor

The function of a monitor is toproduce visual responses to user requests. The monitor is used for displayinginformation on the screen. Most desktop computers use cathode ray tube (CRT)and Liquid Crystal Display (LCD) monitors (see figure below). Recently, CRTmonitors are no longer popular. Most users have replaced them with LCD and LEDmonitors. There are other types, which is a continuous improvement on the LCDmonitor. They include:

1. Light-Emitting Diode (LED) – This is an improvement in LCD monitors.While LCD uses compact florescent tubes to produce picture resolution onthe screen, LED uses back-lighting technology to produce clearer andlifelike images.
2. Organic Light-Emitting Diode (OLED) – This type of monitor is animprovement in the LED monitors. It does not use backlight. This makes itmore energy efficient. Though not popular in monitors, it is availableamong HDTV.
3. Ultra-High Definition Monitors (UHD) – This type of monitor producesexcellent image quality. It is an improvement in the LED monitors. Itimproves on the screen resolution from 2 million pixels (1920 x 1080) to 8million pixels (3240 x 2160).
4. Touchscreen Monitors – This type of monitor performs dual function.It is both an input and an output device. You can use the screen in-placeof the keyboard and the mouse. However, there is still need to use thekeyboard and the mouse when using this type of monitor.

Each dot on the monitor is called a pixel or picture element. A pixel or picture element has the ability to generate red, green, and blue phosphor dots, depending on the signals it receives.

All monitors receive their signals from video cards/adapters attached to the motherboard.

Printer

Printers are devices used to retrieve processed data inhardcopy. Printers place computer processed information on papers and otherhard copy materials. Over time, printer technology has improved to the point atwhich they can produce photo-like images. However, a number of printer technologiesare still in use, due to cost and quality differences between them.

Printers can be categorized based on print technology(dot-matrix, ink-jet, etc), character formation (thermal printers, dot-matrix,laser printers), method of printing (character printers e.g. standarddot-matrix, line printers e.g. ink-jet and bubble-jet, page printers e.g.laser), print capability (text only printers and text and graphics printers). Modernprinters can produce both text and graphics.

The most common category is impact vs. non-impact, and linevs. page printers. Impact printers physically make contact with the paper whilenon-impact printers do not make physical contact with the print paper. Lineprinters print one line at a time while page printers print one page at a time.

The three most common printer technologies are dot matrix,inkjet and bubble jet, and laser printers.

Dot Matrix Printers:Dot matrix printer is aprinter technology that uses a matrix of pins to create dots on the paper. Itis an old type of printer that uses wire-pin print head to produce dots onpaper. Each pin is attached to a solenoid, which, when activated, forcesthe pin toward the paper. As the printhead (which contains the pins) moves across the page, different pins areforced forward to strike a printer ribbonagainst the paper. Because of this action, dot matrix printers fall into the impactprinter category. Furthermore, because their printouts are createdline by line, dot matrix printers are also considered line printers; however, standard dot matrix printers (liketypewriters) are considered character printers because they produce onecharacter at a time.

Disadvantages:

1. Dot matrix printers do not provide a very good resolution (texts and images appeargrainy).

2. They are limited to using color,though color ribbons can be used, theyare limited to using one ribbon at a time. However, modern dot matrix printerscan use up to four ribbons or more.

3. They make noise.

Advantages:

1. They are relatively inexpensive.

2. Because they are impact printers, they can be used formaking carbon duplicate or triplicate forms (usually used in cyclostyling).

3. Because of their simple design, dot matrix printers arealso typically easier to troubleshoot than other printer types.

Inkjet and Bubblejet Printers: Inkjet printers use ink in cartridges, rather than ribbons, tocreate text or graphics printouts. Inkjetprinters create printouts line by line, so they are called line printers. Their print mechanisms do not make contact with thepaper, so they are called non-impact printers. Inkjet printers can combine basic colors to produce a wide range of colors. Although inkjet printers tend to benoisy, they are not as loud as dot matrix printers and they are much faster.Inkjet printers are more expensive than dot matrix printers but cheaper thanlaser printers. A variant of the inkjet printer is the bubble jet printer. Bubble jets are similar to inkjets, buttheir ink cartridges contain heating elements rather than pumps. Generally, theterm inkjet is used to referto all printers that use ink (e.g. inkjets, bubble jets, and desk jets).

Advantages of InkjetPrinters

1. They are portable and handy for small offices
2. They make less noise
3. They are less expensive than laser printers
4. They can print high-qualityphotos

Disadvantages ofInkjet Printers

1. The highcost of replacing ink cartridges
2. The printed ink may smear over someone’s hands
3. Moisture may cause printed inks to smudge

Laser Printers: Laser printer is based on the technology ofa photocopier. They provide the best quality printing and have the mostcomplex structure and process. Thelaser technology uses a laser beam and toner powder to make marks on paper.

Laser printers arethe most commonly used printers, especially in office environments. The laserprinter is a non-impact printer since it does not make contact with thepaper. Given that it creates printouts one page at a time rather than one lineat a time, it is also considered a page printer. Laser printouts donot use dots of color, so they are typically able to provide excellent resolution.Most laser printers print in black and white only. Colour laser printers arealso available but they are more expensive.

Advantages of LaserPrinters

1. They are faster and more efficient
2. They produce a betterquality of output
3. They do not produce unduly noise
4. They are more economical to use.

Disadvantages ofLaser Printers

1. They are costlier when compared with others
2. They are bulky and can take up more office space
3. They are more expensive to maintain
4. They are known to be hazardous to the atmosphere and could cause health challenges

System Unit

The system unit houses the motherboard and other essential components of the computer system. These components are enclosed within the casing to avoid unauthorized touching, as well as prevent dust from entering easily and clogging the components. Some of these components include: Motherboard, CPU, memory card, hard disk drive (HDD), floppy disk drive, CD/DVD drive, cooling fan, video card sound card and Power supply.

Functions of Selected Parts

Motherboard: It houses the BIOS (Basic Input Output System). Itprovides connecting link to every hardware component of the computer system. Itenhances communication between all components attached to it.

Central Processing Unit: The CPU is the brain box of thecomputer system. The CPU controls everything the computer does. It has twomajor components, namely: the Control Unit (CU) and the Arithmetic Logic Unit(ALU). The CU decodes information from the main memory and directs them to theappropriate section for execution; while the ALU is in charge of all mathematicaland logical operations of the computer system.

Cooling fan: It provides a coolingeffect to the CPU. It prevents the CPU from overheating and shutting down thesystem.

Memory card: It is also called RAM (Random Access Memory). Itprovides a temporary storage for data. It also stores information for activelyrunning programs so that data can be accessed and used rapidly. However, datastored in RAM is lost when the system goes out of electric power.

Hard disk drive: It provides a permanent storage space in thecomputer system.

Floppy disk drive: It is used to read or display informationsaved in the diskette. It is also used to write (save) information to thediskette.

CD/DVD drive: CD drive is used to read CDs while the DVD drive is used to read both CDs and DVDs. CDwriter is used to reading and write datato CDs while DVD writer is used to readand write data to both CDs and DVDs.

Video card: It provides a means of connecting themonitor/visual display unit to the motherboard. It also allows the computer toproduce graphics and images.

Soundcard: It provides ameans of connecting the speaker and microphone to the motherboard. It booststhe sound output of the computer system.Power supply: It provides a means ofconnecting the computer system to an electricpower source. Its major function is to convert alternate current (wall voltage)to low-voltage regulated direct current (DC) power for the internal componentsof a computer.

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