Compunter Hardware Components, The IOP cycle, Input Devices, Output Devices Primary and Secondary Storage

1. Computer Hardware

Computer hardware refers to the physical components of a computer system that can be seen and touched. Examples include the keyboard; mouse; monitor; CPU; memory chips and storage devices.

2. Input

Input is the process of entering data and instructions into a computer system for processing. Data can be entered using keyboards; mice; scanners and microphones.

3. Processing

Processing is the manipulation of raw data according to a set of instructions to produce meaningful information. It involves addition; subtraction; multiplication; division; sorting and comparing data.

4. Output

Output is the process of presenting or sending processed information from a computer to a user or another device. Information may be displayed on a monitor; printed on paper or produced as sound through speakers.

5. Storage

Storage is the process of keeping data and information in a computer system for current or future use. Data may be stored temporarily in primary memory or retained for long-term use in secondary storage.

6. Data

Data consists of raw facts and figures that have not yet been processed into meaningful information. Examples include numbers; names; dates; images and measurements.

7. Information

Information is data that has been processed and organised into a meaningful and useful form. For example a report showing a student's average examination mark is information produced from individual marks.

8. Input Device

An input device is a hardware component used to enter data or instructions into a computer system. Examples include keyboards; mice; microphones; scanners and digital cameras.

9. Output Device

An output device is a hardware component that communicates processed information from a computer to a user. Examples include monitors; printers; speakers; headphones; plotters and projectors.

10. Storage Device

A storage device is a hardware component used to save data and programs for later retrieval. Examples include hard disk drives; solid-state drives; USB flash drives; CDs and DVDs.

11. Central Processing Unit (CPU)

The CPU is the main processing component of a computer system. It follows program instructions; processes data and coordinates computer operations. Its two main functional units are the Control Unit and Arithmetic and Logic Unit.

12. Control Unit (CU)

The Control Unit directs and coordinates processing activities within the CPU. It fetches and decodes instructions; determines the sequence in which they are executed and controls the movement of data between the CPU and memory.

13. Arithmetic and Logic Unit (ALU)

The ALU performs arithmetic calculations and logical comparisons. Arithmetic operations include addition; subtraction; multiplication and division. Logical operations include comparing values to determine whether they are equal or whether one is greater or less than another.

14. Fetch-Decode-Execute Cycle

The CPU fetches an instruction from memory and decodes it to determine the required operation. It then obtains any necessary data; executes the instruction and stores the result in a register or memory as required.

15. Primary Memory / Main Memory / Immediate Access Store (IMAS)

Primary memory is memory that the CPU can access directly. It stores data and instructions required during processing. The two main types discussed in the notes are RAM and ROM.

16. Random Access Memory (RAM)

RAM is volatile primary memory that temporarily stores data and instructions currently being used by the CPU. Its contents are normally lost when the computer is switched off.

17. Dynamic Random Access Memory (DRAM)

DRAM is a type of RAM that must be refreshed continuously to retain its stored data. It is commonly used as the main memory in computers.

18. Static Random Access Memory (SRAM)

SRAM is a type of RAM that does not require continuous refreshing while power is supplied. It is generally faster and more expensive than DRAM and is commonly used for cache memory.

19. Read Only Memory (ROM)

ROM is non-volatile memory used to store essential instructions that a computer needs during startup. Unlike RAM it retains its stored contents when power is switched off.

20. Programmable Read Only Memory (PROM)

PROM is a type of ROM that can be programmed once using special equipment. Once programmed its contents cannot normally be changed.

21. Erasable Programmable Read Only Memory (EPROM)

EPROM is a type of ROM whose contents can be erased by exposure to ultraviolet light. It can then be programmed again.

22. Electrically Erasable Programmable Read Only Memory (EEPROM)

EEPROM is a type of ROM whose contents can be erased and reprogrammed electrically without using ultraviolet light.

23. Basic Input/Output System (BIOS)

BIOS is firmware that initialises computer hardware when the computer is switched on and helps begin the process of loading the operating system.

24. Volatile Memory

Volatile memory requires a continuous supply of electricity to retain its contents. When power is removed the stored data is lost. RAM is an example.

25. Non-Volatile Memory

Non-volatile memory retains stored data even when the power supply is switched off. Examples include ROM; flash memory and secondary storage devices.

26. Difference Between RAM and ROM

RAM temporarily stores data and instructions that the computer is currently using. It is volatile and normally allows data to be read and written. ROM stores essential instructions required by the computer and retains its contents without power.

27. Difference Between DRAM and SRAM

DRAM requires frequent refreshing and is commonly used as main memory. SRAM does not require refreshing while powered and is generally faster but more expensive. SRAM is commonly used in CPU caches.

28. Keyboard

A keyboard is an input device used to enter letters; numbers; symbols and commands into a computer. It is commonly used for typing documents; entering data and controlling software.

29. Types of Keyboards

The types include gaming keyboards for gaming controls; wireless keyboards for cable-free communication; mechanical keyboards with individual switches; ergonomic keyboards for comfortable typing; flexible keyboards for portability; multimedia keyboards with media controls; hand keyboards for handheld use and virtual keyboards displayed on screens.

30. Mouse

A mouse is a pointing input device used to control the movement of the pointer on a computer screen. It allows users to select objects; open programs; move icons and interact with menus.

31. Types of Mouse and Related Pointing Devices

Wired mice use cables while wireless mice communicate without data cables. Mechanical mice use rolling balls; scroll-wheel mice have scrolling controls; optical mice use light sensors; laser mice use laser tracking; BlueTrack mice use blue-light tracking and gaming mice have specialised controls. Trackballs use rotating balls while touchpads are touch-sensitive surfaces.

32. Joystick

A joystick is an input device consisting of a lever that can be moved in different directions to control objects or movement on a screen. It is mainly used in computer games; simulations and specialised control systems.

33. Pointing Device

A pointing device is an input device used to control the pointer or cursor and select objects on a graphical display. Examples include mice; trackballs; touchpads; joysticks; light pens; digitising tablets and touchscreens.

34. Optical Mark Recognition (OMR)

OMR is a technology used to detect marks made in predetermined positions on paper. It works by measuring reflected light and is commonly used to process multiple-choice examinations; surveys; election ballots and lottery tickets.

35. Magnetic Ink Character Recognition (MICR)

MICR is a technology used to read characters printed with special magnetic ink. It is mainly used in banking to process cheques and read information such as cheque numbers; bank codes and account numbers.

36. Optical Character Recognition (OCR)

OCR is a technology that uses scanning and recognition software to convert printed or handwritten characters into machine-readable text. It allows scanned text to be edited; searched and processed electronically.

37. Barcode Reader

A barcode reader is an input device used to scan and interpret barcodes printed on products or documents. It is used in supermarkets; libraries; warehouses; airports and postal services for fast and accurate data entry.

38. Document Scanner

A document scanner is an input device that converts printed text; photographs or other paper documents into digital images. The scanned information can then be stored or processed by a computer.

39. Flatbed Scanner

A flatbed scanner is a scanner in which a document is placed on a flat glass surface for scanning. It is commonly used to scan photographs; books and printed documents.

40. Handheld Scanner

A handheld scanner is a portable scanning device moved across the document or image being scanned. It is useful for capturing information quickly but manual movement can affect image quality.

41. Sheet-Fed Scanner

A sheet-fed scanner automatically pulls paper through rollers while scanning its contents. It is useful for scanning large numbers of loose paper documents.

42. Drum Scanner

A drum scanner uses a rotating drum to capture images at very high resolution. It has been used in professional publishing and graphic production where detailed image reproduction is required.

43. Light Pen

A light pen is a pen-shaped pointing input device containing a light-sensitive component. It can detect a position on a compatible display screen and is used to select objects or draw directly on the screen. It is largely obsolete with modern displays.

44. Touchscreen / Touch Terminal

A touchscreen is a display that also acts as an input device by detecting where a user touches its surface. It allows users to select commands and enter information directly. Examples include ATMs; tablets; smartphones and point-of-sale terminals.

45. Voice Recognition / Voice Data Entry

Voice recognition is a technology that allows a computer to recognise spoken words and commands using a microphone and recognition software. It can be used for dictation; controlling applications and assisting users with physical disabilities.

46. Digitising Tablet / Graphics Tablet

A digitising tablet is an input device used to convert drawings or handwritten movements into digital information. It is commonly used by architects; graphic designers; artists and mapmakers.

47. Stylus

A stylus is a pen-shaped input tool used with a touchscreen or digitising tablet. It allows users to write; draw and select objects with greater precision than a finger.

48. Puck

A puck is a mouse-like pointing device used with some digitising tablets. It allows users to select positions and trace drawings or maps accurately.

49. Point of Sale (POS) System

A POS system is a computerised system used to record and process retail sales transactions. It may combine a barcode reader; computer; cash register; payment equipment and sales software. It provides quicker service; improves transaction accuracy; updates stock records and supports sales analysis.

50. Digital Camera

A digital camera is an input device used to capture photographs electronically. Its image sensor converts light into electrical signals that are processed into digital images. These images can be stored and transferred to a computer for editing or printing.

51. Image Resolution

Image resolution refers to the amount of detail contained in a digital image. It is commonly expressed in pixels. Images with more pixels can generally capture greater detail although image quality also depends on other factors.

52. Biometric System

A biometric system identifies or verifies a person using distinctive physical or behavioural characteristics. Examples include fingerprints; iris patterns; facial features; hand geometry and voice patterns. Biometric systems are used for identification and security.

53. Sensor

A sensor is an input device that detects physical or environmental conditions and converts them into signals that can be processed by a computer. Sensors may measure temperature; light; sound; pressure; humidity; acidity; oxygen concentration; movement; pulse rate; water level and speed. They are used in medicine; weather monitoring and industrial control systems.

54. Remote Control

A remote control is an input device used to transmit commands to electronic equipment from a distance. Many remote controls transmit signals using infrared light. They are used with televisions; audio systems and other electronic devices.

55. Microphone / Sound Capture Device

A microphone is an input device that captures sound and converts it into electrical signals. These signals can be digitised for storage or processing by a computer. Microphones are used for voice recording; video calls and speech recognition.

56. Webcam

A webcam is an input device that captures video images and sends them to a computer or network. It is commonly used for video conferencing; online communication and security surveillance.

57. Human-Readable Output

Human-readable output is information presented in a form that people can understand directly. Examples include text displayed on a monitor; printed documents and sound from speakers.

58. Machine-Readable Output

Machine-readable output is information produced in a form intended to be interpreted or processed by another machine or computer system rather than directly by a person.

59. Softcopy Output

Softcopy output is information presented electronically without creating a permanent physical copy. Examples include text displayed on a monitor; images projected onto a screen and sound produced through speakers.

60. Hardcopy Output

Hardcopy output is information produced in a physical form that can be handled and retained. Examples include printed documents; photographs and drawings.

61. Monitor / Visual Display Unit (VDU)

A monitor is an output device that displays text; pictures; graphics and videos produced by a computer. It allows users to view information and interact with computer applications.

62. Cathode Ray Tube (CRT) Monitor

A CRT monitor is an older type of display that produces images by directing electron beams onto a phosphor-coated screen. It is generally large; heavy and less energy-efficient than modern flat-panel monitors.

63. Flat-Panel Display

A flat-panel display is a thin screen used to present visual information electronically. Common technologies include LCD; LED-backlit LCD and plasma displays. These screens generally occupy less space than CRT monitors.

64. Liquid Crystal Display (LCD)

An LCD is a flat-panel display that uses liquid crystals to control the passage of light and produce images. It generally consumes less electricity; occupies less space and produces less heat than a CRT monitor.

65. LED Display / LED Monitor

An LED monitor commonly refers to an LCD monitor that uses light-emitting diodes for backlighting. Compared with older fluorescent-backlit LCD monitors it can offer better energy efficiency and improved picture quality.

66. Plasma Display

A plasma display is a flat-panel display technology that uses electrically charged gas cells to produce visible light. Plasma displays were commonly used in large televisions but have largely been replaced by newer display technologies.

67. Difference Between LCD and LED Monitors

A traditional LCD monitor uses fluorescent lamps for backlighting while an LED-backlit LCD monitor uses light-emitting diodes. Both use liquid crystals to produce images. LED backlighting can provide better energy efficiency and display performance.

68. Audio Output Device

An audio output device converts a computer's audio signals into sound that can be heard. Examples include speakers; headphones and earphones.

69. Speakers

Speakers are output devices that convert electrical audio signals into audible sound. They are used for playing music; videos; notifications and other audio from a computer.

70. Headphones

Headphones are audio output devices worn over or on the ears. They allow users to listen to computer-generated sound more privately without disturbing others.

71. Earphones

Earphones are small audio output devices placed in or near the ears. They perform a similar function to headphones but are generally smaller and more portable.

72. Printer

A printer is an output device that produces a hardcopy of text; images or graphics on paper or another physical material.

73. Character Printer

A character printer prints one character at a time. It is generally slower than printers that produce entire lines or pages. An example is a daisy-wheel printer.

74. Line Printer

A line printer prints an entire line of text at a time. It is used for producing large volumes of text-based output. Traditional examples include drum; chain and band printers.

75. Page Printer

A page printer prepares and prints a whole page of information as a unit. Laser printers are common examples and can produce high-quality text and graphics.

76. Impact Printer

An impact printer produces output by striking an inked ribbon against paper. Examples include dot-matrix; daisy-wheel; drum; chain and band printers.

77. Non-Impact Printer

A non-impact printer produces output without mechanically striking an inked ribbon against paper. It is generally quieter than an impact printer and can produce high-quality text and graphics. Examples include inkjet; laser and thermal printers.

78. Dot-Matrix Printer

A dot-matrix printer is an impact printer that forms characters and images using patterns of small dots. Pins in its print head strike an inked ribbon against paper. It is noisy and commonly used for multipart forms and continuous stationery.

79. Daisy-Wheel Printer

A daisy-wheel printer is an impact printer that uses a rotating wheel containing fixed characters. A hammer strikes the selected character against an inked ribbon to print it. It produces clear text but is slow; noisy and largely obsolete.

80. Drum Printer

A drum printer is a type of impact line printer that uses a rotating drum containing raised characters. Hammers strike the paper and ribbon when the required characters move into position. It is suitable for printing large volumes of text.

81. Chain Printer

A chain printer is an impact line printer that uses a rotating chain containing characters. Hammers strike the appropriate characters through an inked ribbon to produce printed lines.

82. Band Printer

A band printer is an impact line printer that uses a rotating band containing characters. It works similarly to a chain printer and is designed for high-volume text printing.

83. Inkjet Printer

An inkjet printer is a non-impact printer that produces text and images by spraying tiny droplets of ink onto paper. It can produce colour photographs and documents and is commonly used in homes and small offices.

84. Laser Printer

A laser printer is a non-impact printer that uses a laser-based imaging system and powdered ink called toner to produce high-quality text and graphics. Heat and pressure fuse the toner onto paper. Laser printers are commonly used in offices and schools.

85. Thermal Printer

A thermal printer is a non-impact printer that uses heat to produce printed output. Some print directly onto heat-sensitive paper while others use heat to transfer ink from a ribbon. They are commonly used for receipts and labels.

86. Difference Between Impact and Non-Impact Printers

Impact printers use physical striking mechanisms to produce output and are generally noisy. Non-impact printers produce output without striking an inked ribbon against paper and are generally quieter. Impact printers are useful for certain multipart forms while non-impact printers are widely used for ordinary documents and graphics.

87. Plotter

A plotter is an output device used to produce large or detailed graphical documents. It is commonly used to create architectural drawings; engineering plans; maps and charts.

88. Pen Plotter

A pen plotter uses a pen attached to a mechanical arm or rail to draw lines on paper. It produces precise line drawings and has been used for technical diagrams.

89. Inkjet Plotter

An inkjet plotter produces large-format drawings and images by spraying tiny droplets of ink onto paper. It is commonly used for posters; architectural drawings and maps.

90. Electrostatic Plotter

An electrostatic plotter uses electrical charges and toner to form images on paper. It can produce large technical drawings and operates using principles similar to electrostatic printing.

91. Computer Output on Microfilm / Microfiche (COM)

COM is a method of recording computer-generated information onto photographic film in a greatly reduced size. It allows large volumes of documents to be stored compactly and viewed using specialised equipment.

92. Microfilm

Microfilm is a roll of photographic film used to store reduced images of documents. It allows many pages of information to be preserved in a small space.

93. Microfiche

Microfiche is a flat rectangular sheet of photographic film containing multiple reduced images of documents. The information is viewed using a special magnifying reader.

94. Projector

A projector is an output device that displays computer-generated images or videos onto a large surface such as a wall or projection screen. It is commonly used in classrooms; meetings and presentations.

95. Secondary Storage

Secondary storage is non-volatile storage used to retain data; programs and information for future use. Unlike RAM it keeps stored information when the computer is switched off.

96. Magnetic Storage

Magnetic storage is a method of storing data by magnetising areas of a recording surface. Examples include hard disk drives; floppy disks and magnetic tapes.

97. Magnetic Disk

A magnetic disk is a circular storage medium coated with magnetic material. Data is recorded on its surface and accessed using read/write heads.

98. Read/Write Head

A read/write head is a component that reads stored data from a recording medium and writes new data onto it. It is used in magnetic storage devices such as hard disk drives.

99. Floppy Disk

A floppy disk is a removable magnetic storage medium enclosed in a protective casing. A common 3.5-inch floppy disk stores approximately 1.44 MB of data. It is rewritable but has low capacity and is easily damaged compared with modern storage devices.

100. Hard Disk Drive (HDD)

A hard disk drive is a magnetic storage device containing rotating platters coated with magnetic material. Read/write heads access the stored data. It is commonly used for long-term storage of operating systems; applications and user files.