Study sheet: Computer Input Devices

📋 Course Outline

1. Computer Definition and Categories
2. Computers for Individual Users
3. Computers for Organizations
4. Computers and Social Information
5. Computers Across Society
6. Complete Computer System
7. Information Processing Cycle
8. Core Hardware Components
9. Storage and Peripheral Devices
10. Software and Computer Data
11. Keyboard Layout and Key Groups
12. Keyboard Input Processing
13. Mouse Techniques and Variants
14. Stationary Pointing Devices
15. Shortcuts and Ergonomics
16. Handheld Alternative Inputs
17. Optical and Audio Input
18. Speech Recognition and Audio Input

📖 1. Computer Definition and Categories

🔑 Key Concepts & Definitions

• Computer : an electronic device that processes data, converting it into information useful to people, and is controlled by programmed instructions that give it a purpose.

★ Must-know

📌 Digital computers represent information numerically as distinct values and process each unit in strict sequences, whereas analog computers represent data as variable points along a continuous spectrum.

Further detail

• Computers can be categorized by:
  • their intended number of users
  • their power
  • their price
  • their hardware
  • the software they can run

💡 Memory Hook

Digital computers use distinct values; analog computers use a continuous spectrum.

📖 2. Computers for Individual Users

🔑 Key Concepts & Definitions

• Personal computer : a computer system designed for use by a single person and is also called a microcomputer.

★ Must-know

• The six primary types of individual-use computers are:

  • desktop computers
  • workstations
  • notebook computers
  • tablet computers
  • handheld computers
  • smart phones

• Notebook computers are fully functional mobile microcomputers that fold closed, operate on alternating current or batteries, and generally weigh less than eight pounds.

Further detail

📌 A workstation is a specialized single-user computer with more power and features than a standard desktop PC, typically serving scientists, engineers, and animators who perform sophisticated tasks.

• Tablet PCs provide notebook functionality in a lighter form and accept input through a stylus, digital pen, voice input, or, in some models, a fold-out keyboard.

• Handheld computers are small enough to fit in a hand and can provide applications such as note-taking, contact management, scheduling, wireless Internet access, telephone service, cameras, music players, and global positioning.

💡 Memory Hook

Desktop, workstation, notebook, tablet, handheld, smartphone.

📖 3. Computers for Organizations

🔑 Key Concepts & Definitions

• Network server : usually a powerful personal computer with specialized software and equipment that functions as the primary computer in a network.

★ Must-know

• The four primary organizational computer types are:
  • network servers
  • mainframe computers
  • minicomputers
  • supercomputers

📌 A dumb terminal is only an input/output device with no data processing or storage, whereas an intelligent terminal can perform some processing but usually has no storage.

• Mainframe computers are large, powerful systems used by organizations such as banks and insurance companies to provide shared data and tasks for thousands of users, usually through terminals.

• Supercomputers are the most powerful computers made, with the fastest systems performing more than one trillion calculations per second for complex problems such as weather forecasting, human-genome mapping, and nuclear-fission modeling.

Further detail

• Minicomputers, also called midrange computers, have capabilities between those of mainframes and personal computers and can serve the input and output needs of hundreds of users.

💡 Memory Hook

Servers emphasize flexible shared services, whereas mainframes emphasize powerful specialized tasks.

📖 4. Computers and Social Information

🔑 Key Concepts & Definitions

• Information : Information includes facts, formulas and results, building plans, recipes, pictures, songs, addresses, games, menus, shopping lists, and resumes that computers can store and process.

★ Must-know

• Computers are important because they help people work with information and create new information.

Further detail

• Computers enable people with disabilities to communicate, learn, or work without leaving home, help sales professionals communicate and manage leads and schedules, and perform time-consuming calculations for researchers.

💡 Memory Hook

More information needs → greater reliance on computers.

📖 5. Computers Across Society

★ Must-know

• Home computers are used for:

  • communications
  • work performed at home
  • schoolwork
  • entertainment
  • personal finances

• Industry uses computers for:

  • computer-aided design and manufacturing
  • shipping management
  • process control of production systems

• Health care uses computers for: ultrasound, magnetic resonance imaging, laser eye surgery, fetal monitoring, robotic and remote surgery, surgeon training, patient records, scheduling, and billing, transactions among physicians, insurers, and pharmacies

Further detail

• Small businesses use inexpensive computers and software for accounting, inventory management, marketing, payroll, and other tasks that can reduce operating expenses.

• Government agencies use computers for:

  • population counting
  • tax filing and calculation
  • military operations
  • police access to information

📖 6. Complete Computer System

🔑 Key Concepts & Definitions

• Complete computer system : hardware, software, data, and a user
• Hardware : any physical, touchable part of a computer, including interconnected electronic devices used for input, output, and control
• Software : a set of instructions that tells a computer what to do and enables it to perform tasks

★ Must-know

📌 Data are individual facts or pieces of information that may lack meaning by themselves, whereas information is data placed in a useful context.

Further detail

• People remain essential to computer systems because they design, build, program, repair, start, and direct computers, even when the systems operate without continuous supervision.

💡 Memory Hook

HSDU: Hardware, Software, Data, User

📖 7. Information Processing Cycle

🔑 Key Concepts & Definitions

• Input : the stage during which a computer accepts data from a user, a program, or another computer system
• Processing : the stage during which computer components act on data according to instructions from a user or a program

★ Must-know

• 🔄 The information processing cycle consists of:
  1. Input
  2. Processing
  3. Output
  4. Storage

Further detail

📌 Output and storage are optional stages that occur when the user or program requires them.

💡 Memory Hook

Input → Processing → Output → Storage

📖 8. Core Hardware Components

🔑 Key Concepts & Definitions

• Central processing unit : the computer's processor, usually consisting of one or more microprocessors that organize and execute instructions

★ Must-know

• Computer hardware falls into four categories:
  • Processor
  • Memory
  • Input and output
  • Storage

📌 RAM temporarily holds data and program instructions being used by the CPU, whereas ROM permanently stores instructions needed for startup and hardware information.

Further detail

• RAM is volatile and loses its contents when the computer is shut off or loses power.

• Larger memory capacities are commonly expressed in:

  • Kilobytes
  • Megabytes
  • Gigabytes
  • Terabytes

💡 Memory Hook

RAM is temporary and volatile, whereas ROM is permanent and non-volatile.

📖 9. Storage and Peripheral Devices

★ Must-know

📌 Storage retains data when the computer is turned off and offers more capacity at lower cost, whereas memory is faster but temporary and more expensive.

📌 Magnetic storage uses disks and read/write heads, whereas optical storage uses lasers to read or write data on reflective discs.

Further detail

• A standard CD can store about 74 minutes of audio or 650 MB of data, while newer CDs can store 80 minutes of audio or 700 MB of data.

• DVDs can store between 4.7 GB and 17 GB of data and can hold a full-length movie on a disc the same size as a compact disc.

💡 Memory Hook

Magnetic storage uses read/write heads, whereas optical storage uses lasers.

📖 10. Software and Computer Data

🔑 Key Concepts & Definitions

• Operating system : essential system software that acts as an interpreter between hardware, application programs, and the user

★ Must-know

📌 System software controls hardware and maintains the computer, whereas application software helps users perform specific tasks.

• The three basic types of system software are:
  • Operating systems
  • Network operating systems
  • Utilities

📌 Data are pieces of information without context, programs are instructions for computers, and files are named sets of data or program instructions.

Further detail

• Major categories of application software include:
  • Word processing
  • Spreadsheets
  • Database management
  • Presentation programs
  • Graphics
  • Multimedia authoring
  • Web tools
  • Entertainment and education software
  • Games

💡 Memory Hook

System software runs and manages the computer, whereas application software serves user tasks.

📖 11. Keyboard Layout and Key Groups

🔑 Key Concepts & Definitions

• Keyboard : an input device with about 100 keys that sends signals to the CPU and remains the primary device for entering text and numbers

★ Must-know

• The five keyboard groups are:
  • alphanumeric keys
  • modifier keys
  • numeric keypad
  • function keys
  • cursor-movement keys

📌 Modifier keys change the input of another key: SHIFT can produce a capital letter or symbol, ALT supports menu and dialog navigation, and CTRL commonly provides shortcuts for menu commands.

Further detail

• The alphanumeric group includes four additional function keys:

  • TAB
  • CAPS LOCK
  • BACKSPACE
  • ENTER

• The numeric keypad contains ten digits and mathematical operators, and NUM LOCK switches its keys between numeric input and cursor-control or other functions.

• Function keys such as F1 provide program-dependent commands, with F1 commonly opening help, while cursor-movement keys move the insertion point through a document.

📖 12. Keyboard Input Processing

🔑 Key Concepts & Definitions

• Keyboard buffer : a temporary memory area that stores key codes until the computer can process them

★ Must-know

• 🔄 Keyboard input follows this sequence:
  1. The keyboard controller detects a pressed key.
  2. The controller stores the key code in the keyboard buffer.
  3. The controller signals the system software.
  4. The system software reads the code from the buffer.
  5. The system software passes the code to the CPU.

Further detail

• The keyboard buffer can hold multiple keystrokes so programs can respond when convenient despite the delay between pressing a key and reading its code.

• The keyboard repeat rate determines how long an alphanumeric key must be held before its character repeats and how quickly the character is retyped.

💡 Memory Hook

Key press → buffer code → system software → CPU

📖 13. Mouse Techniques and Variants

🔑 Key Concepts & Definitions

• Mouse : an input device moved across a flat surface to control an on-screen pointer used to select text, access menus, and interact with programs, files, or data
• Trackball : a stationary pointing device operated by rolling an exposed ball with a finger or thumb, so it requires less space than a mouse
• Trackpad : a stationary pointing device that translates finger movement across a touch-sensitive surface into pointer movement

★ Must-know

• The essential mouse techniques are:
  • pointing
  • clicking
  • double-clicking
  • dragging
  • right-clicking

📌 Clicking selects an object, double-clicking commonly launches a desktop object, dragging moves an item while holding the primary button, and right-clicking usually opens a shortcut menu.

Further detail

📌 A mechanical mouse uses a rubber ball, rollers, and sensors to detect movement, whereas an optical mouse uses reflected light to measure its distance, direction, and speed.

💡 Memory Hook

Mouse moves; trackball and trackpad stay stationary

📖 14. Stationary Pointing Devices

🔑 Key Concepts & Definitions

• Trackball : A pointing device that works like an upside-down mouse: the user rolls an exposed ball with a finger or thumb while the device remains stationary.
• Integrated pointing device : A small joystick built into a portable computer keyboard, typically between the G and H keys, that controls the on-screen pointer without requiring the user's hands to leave the keyboard.

📝 Essential Points

• Trackpads usually have two or three buttons with functions like mouse buttons, and some are strike-sensitive so users can tap the pad instead of pressing its buttons.

• On IBM ThinkPad computers, the integrated pointing device is called the TrackPoint, and two buttons beneath the spacebar perform mouse-button functions.

💡 Memory Hook

Trackball rolls; trackpad glides; keyboard joystick stays under the fingers.

📖 15. Shortcuts and Ergonomics

🔑 Key Concepts & Definitions

• Keyboard shortcut : A short combination of keystrokes, usually involving a modifier key such as ALT or CTRL, that issues a command quickly.
• Ergonomics : The study of the physical relationship between people and their tools, including computers, to reduce strain and injuries through suitable designs and techniques.
• Carpal tunnel syndrome : A repetitive stress injury in which inflamed tendons in the wrist's carpal tunnel press against nerves, causing tingling, numbness, pain, or inability to use the hands.
• Macro : A series of commands that a program memorizes so the user can issue the entire set with only a few keystrokes.

★ Must-know

• To reduce keyboard-related injuries, users should keep their wrists straight, sit upright with their feet flat, type rather than hunt and peck, take frequent breaks, and use suitably arranged ergonomic equipment.

Further detail

• In many applications, CTRL+P prints a document, F1 opens online help, and pressing ALT activates the Windows menu bar.

💡 Memory Hook

Poor posture and repetitive use → strain, fatigue, and repetitive stress injuries.

📖 16. Handheld Alternative Inputs

🔑 Key Concepts & Definitions

• Pen-based system : A system that uses a pen or stylus to write, draw, tap, or select commands on a special pad or directly on a screen.
• Touch screen : A screen that accepts input when the user places a fingertip directly on it, usually to select an item from a menu.

★ Must-know

📌 Game controllers generally fall into two categories: joysticks, which direct vehicles or characters and are popular in racing and flying games, and game pads, which are small flat devices with controls for both hands.

Further detail

• Pen-based computers are commonly used for notes, short messages, annotations, data collection, and signatures stored or transmitted as graphic images.

• Touch screens are suited to dirty or weather-exposed environments and simple applications such as automated teller machines, public information kiosks, restaurants, stores, and supermarkets.

💡 Memory Hook

Pen → touch screen → game controller

📖 17. Optical and Audio Input

🔑 Key Concepts & Definitions

• Bar code reader : A device that emits light, often a laser beam, detects the reflected bar pattern, converts it into numeric digits, and sends the data to a computer as if it had been typed.
• Image scanner : A device that converts a printed image into electronic form by shining light on it and sensing the intensity of reflected light at every point.
• Optical character recognition : Translates a bitmap of a scanned text document into letters and numbers that a computer can edit.
• Speech recognition : Also called voice recognition, translates spoken words into text and allows users to control a computer with commands such as Open or Cancel.
• Sound card : Translates analog audio signals from a microphone into digital codes that a computer can store and process, and can convert digital sounds back into analog signals for speakers.

★ Must-know

• Speech-recognition systems are trained by having a user read passages into a microphone so the computer learns the user's pronunciation of phonemes and combines them into words, usually with a dictionary.

Further detail

• A scanned image is initially stored as a bitmap, a grid of dots in which each dot is represented by one or more bits.

• Color scanners use filters to separate red, green, and blue components at each point, and these primary additive colors can be combined to create other colors.

• Even the best trained speech-recognition systems provide better than 99 percent accuracy, which can still mean as many as one recognition mistake for every 100 sounds.

💡 Memory Hook

Light reads codes and images; sound becomes digital data and text.

📖 18. Speech Recognition and Audio Input

🔑 Key Concepts & Definitions

• Speech recognition : translates spoken words into text or commands, allowing users to dictate instead of typing and to control a computer with commands such as Open or Cancel
• Webcam : a popular, inexpensive PC video camera that can sit on a monitor or stand and capture images for uses such as videoconferencing
• Video capture card : connects devices such as VCRs and camcorders to a PC, allowing images to be transferred between the video equipment and the computer
• Digital camera : a portable device that captures still images electronically, digitizes and compresses them, and stores them on a memory card for transfer to a PC

★ Must-know

• To record a voice file, a user connects a microphone, records the sound with audio software, and saves the resulting file on disk for use in documents, Web pages, or e-mail.

• Some speech-recognition packages recognize 80 to 90 percent of spoken words with large stored vocabularies, may require user training, and can recognize continuous speech without pauses between words.

• A computer video camera digitizes images by breaking them into pixels, storing each pixel’s color and other characteristics as digital code, and compressing the code for storage or network transmission.

• Hardware maintenance technicians install and configure new hardware, install peripherals, upgrade computers, handle network-related hardware issues, and troubleshoot and repair hardware.

Further detail

• Speech-recognition software analyzes phonemes, but reliable translation is difficult because English has about 40 phonemes, some words sound alike, and background noise can obscure meaningful sounds.

• Noise-canceling microphones are commonly required by speech-recognition programs because they filter out background noise.

• Digital-camera images can be:

  • edited
  • copied
  • printed
  • embedded in documents
  • transmitted to another user

• Hardware technicians commonly build systems from the system board upward, configure and test the machines, and prepare them for customer use.

• 🔄 The Sound Recorder exercise follows these steps:

  1. Open Sound Recorder through Start, Accessories, Entertainment, and Sound Recorder
  2. Click Record and speak into the microphone
  3. Click Stop
  4. Click Play to hear the message
  5. Close the program and choose whether to save the file

💡 Memory Hook

Analog sound → digitizing → stored or processed digital audio

📊 Synthesis Tables

RAM and ROM

Feature	RAM	ROM
Purpose	Working data and program instructions	Startup instructions and hardware information
Power dependence	Volatile; loses contents without power	Non-volatile; retains contents without power
Access	Read and write	Primarily read-only

Alternative Input Types

Device	Primary input	Typical uses
Pen-based system	Handwriting, tapping, signatures	Notes, annotations, data collection
Touch screen	Finger selections	ATMs, kiosks, retail systems
Bar code reader	Reflected light from bar patterns	Product and package identification
Image scanner	Reflected light from printed images	Digitizing photos and documents
Speech-recognition system	Spoken words	Dictation and computer commands