computer systemconcepts
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COMPUTER SYSTEM
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What is Computer?Computer
- an electronic device capable of interpreting and executing programmed commands. It includes both hardware (physical equipment) and software ( instructions that tell the hardware what to do)
Computer System – a collection of interrelated devices that work together to transform data into information.
Data – characters, symbol, or other raw, unrecognized material.
Information – data organized into useful, meaningful form
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Four Basic Functions
Input – gathering data and communicating the data to the computer
Processing – transforming data into meaningful for by performing various operations.
Output – display the data once it has been processed
Storage – storing the result of processing so that they can be used at a later time
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The Central Processing Unit (CPU)- the part of the computer that processes data and controls the other parts of the computer system
Two (2) basic Parts1. Arithmetic Logic unit – processes data
by manipulating numbers, letters, and symbols.
2. Control Unit – coordinates and controls the other parts of the computer system
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How computer represents and stores data?
Binary system – a system that uses just two symbols to represent all information
Bit – a zero or one
Bytes – a string of 8-bits, typically representing one character of information
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How do we use Computers?
1. Information system/data processing
– computer-based information that provides organization with data processing capabilities and the knowledge workers in the organization with the information they need to make a better informed decisions.
- combined hardware, software, people, procedures, and data.
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How do we use Computers?
2. Personal Computing
- the single-user micro used for a variety of business and domestic such as
Word processing Desktop publishing Spreadsheet software Database software Graphic software
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How do we use Computers?
2. Science, research, and engineering
- the computer is used as a tool in experimentation, design and development.
3. Process/ Device Control
- applications that involve process.
4. Education
- the computer interacts with a student to enhance the learning process
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How do we use Computers?
5. Computer-Aided Design (CAD) – using the computer in the design process.
6. Entertainment - computer applications are being designed and created just to entertain us.
7. Artificial intelligence - creating computer system with the ability to reason, learn, or to accumulate knowledge, to strive for self-improvement, and to stimulate human- sensory and mechanical capabilities.
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SHAPES OF COMPUTERS
• Supercomputers
• Mainframe Computers
• Minicomputers
• Workstations
• Microcomputers, or Personal Computers
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Supercomputers
•Supercomputers are the most powerful computers. They are used for problems requiring complex calculations.
•Because of their size and expense, supercomputers are relatively rare.
•Supercomputers are used by universities, government agencies, and large businesses.
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Mainframe Computers
• Mainframe computers can support hundreds or thousands of users, handling massive amounts of input, output, and storage.
• Mainframe computers are used in large organizations where many users need access to shared data and programs.
• Mainframes are also used as e-commerce servers, handling transactions over the Internet.
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Minicomputers
• Minicomputers are smaller than mainframes but larger than microcomputers.
• Minicomputers usually have multiple terminals.
• Minicomputers may be used as network servers and Internet servers.
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Workstations
• Workstations are powerful single-user computers.
• Workstations are used for tasks that require a great deal of number-crunching power, such as product design and computer animation.
• Workstations are often used as network and Internet servers.
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Microcomputers, or Personal Computers
• Microcomputers are more commonly known as personal computers. The term "PC" is applied to IBM-PCs or compatible computers.
• Full-size desktop computers are the most common type of PC.
• Notebook (laptop) computers are used by people who need the power of a desktop system, but also portability.
• Handheld PCs (such as PDAs) lack the power of a desktop or notebook PC, but offer features for users who need limited functions and small size.
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Using Computers - in the home
This refrigerator allows customers - from their kitchens - to access selected retailers, order, scan and purchase goods, pay their bills, even watch television and send e-mail messages
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A computer is a tool
A computer is not intelligent
Everything it does come from instructions it receives from a person.
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A complete computer system includes four distinct parts:
Hardware
Software
Data
User
What is Computer?
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computer system
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Hardware
• A computer's hardware consists of electronic devices; the parts you can see and touch.
• The term "device" refers to any piece of hardware used by the computer, such as a keyboard, monitor, modem, mouse, etc.
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A computer's hardware devices are categorized as follows:
• Processor
• Memory
• Input and output (I/O) devices
• Storage devices
• Communication devices
Types of Hardware
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Primary Memory and Processor
- stores data temporarily and works closely with the CPU.
RAM
ChipProcessor
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Input Device
A device which takes in data and program instructions and converts them into digital form
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keypad at a bank machine
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• A standard computer keyboard has about 100 keys.
• Most keyboards use the QWERTY layout, named for the first six keys in the top row of letters.
The Keyboard - Standard Keyboard Layout
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5. Cursor-movement keys
4. Modifier keys
3. Function keys
2. Numeric keypad
1. Alphanumeric keys
Most keyboards have keys arranged in five groups:
The Keyboard - Standard Keyboard Layout
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ACADEMIC RECORDS
Password
ENTER Invalid Password
* * * * *
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• Long periods of keyboard use can cause injuries.
• An ergonomically correct keyboard can help you avoid injuries.
• You also can avoid injuries by adopting correct keyboarding practices.
The Keyboard - Ergonomic Keyboards
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• The keyboard controller detects the keystroke.
• The controller places a scan code in the keyboard buffer, indicating which key was pressed.
• The keyboard sends the computer an interrupt request, telling the CPU to accept the keystroke.
When you press a key:
The Keyboard - How a Keyboard Works
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The Mouse
• What is a Mouse?
• Mouse Techniques
Pointing Devices
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The Mouse - What is a Mouse?
• The mouse is a pointing device. You use it to move a graphical pointer on the screen.
• The mouse can be used to issue commands, draw, and perform other types of input tasks.
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The Mouse - Mouse Techniques
1. Pointing; Move the mouse to move the on-screen pointer.
2. Clicking; Press and release the left mouse buttononce.
3. Double-clicking; Press and release the left mousebutton twice.
4. Dragging; Hold down the left mouse button as youmove the pointer.
5. Right-clicking; Press and release the right mouse button.
Using the mouse involves five techniques:
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Variants of the Mouse
• Trackballs
• Trackpads
• Integrated Pointed Devices
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Trackballs
• A trackball is like a mouse turned upside-down.
• Use your thumb to move the exposed ball and your fingers to press the buttons.
Many styles of trackball are available.
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Trackpads
• A trackpad is a touch-sensitive pad that provides the same functionality as a mouse.
• To use a trackpad, you glide your finger across its surface.
• Trackpads provide a set of buttons that function like mouse buttons.
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Integrated Pointing Devices
• An integrated pointing device is a small joystick built into the keyboard.
• To use an integrated pointing device, you move the joystick.
• These devices provide a set of buttons that function like mouse buttons
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Alternative Input Devices – Devices for the Hand
• Pens
• Touch Screens
• Game Controllers
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Pens
• With a pen-based system, you use an electronic pen to write on the screen and choose commands.
• Pens are common input devices for handheld computers, like “personal digital assistants (PDAs).”
• Pens are handy for making notes or selecting commands, not for inputting a lot of text.
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The user can point, tap, draw and write on the
computer’s screen with a pen.
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Touch Screens
• Touch-screen systems accept input directly through the monitor.
• Touch screens use sensors to detect the touch of a finger. They are useful where environmental conditions prohibit the use of a keyboard or mouse.
• Touch-screen systems are useful for selecting options from menus.
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Game Controllers
• The two primary types of game controllers are joysticks and game pads.
• Game pads usually provide controls for each hand.
• Joysticks are popular for flight simulator and driving games.
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Joystick
Game pad
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Alternative Input Devices –Optical Input Devices
• Bar Code Readers
• Image Scanners and OCR
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Bar Code Readers
• Bar code readers can read bar codes—patterns of printed bars.
• The reader emits light, which reflects off the bar code and into a detector in the reader. The detector translates the code into numbers.
• Flatbed bar code readers are commonly found in supermarkets. Courier services often use handheld readers.
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Bar code readers commonly track
sales in retail stores
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Image Scanners and OCR
• Image scanners digitize printed images for storage and manipulation in a computer.
• A scanner shines light onto the image and interprets the reflection.
• Optical character recognition (OCR) software translates scanned text into editable electronic documents.
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Hand-held scanner – read data on price tags, shipping labels, inventory part numbers, book ISBN and the like. Sometimes called “wand scanner”
Bar code
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Stationary label scanner – rely exclusively on laser technology and are used in the same type of application as wand scanners.
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Page scanners – used to translate printed hard copy to machine-readable format.
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Document scanner – capable of scanning documents of various sizes ( utility bill invoice stubs and sales slips from credit card transactions)
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Continuous-form scanner – read data printed on continuous forms such as cash register tapes.
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Optical mark scanner – can preprinted forms, such as multiple-choice test answer forms.
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Other Scanners
Retinal/Iris Scanner
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Other Scanners
Signature Scanner
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Other Scanners
Fingerprint Scanner
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Other Scanners
Fingerprint Scanner
Door LockTime Attendance
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Alternative Input Devices – Audio-Visual (Multimedia) Input Devices
• Microphones and Speech Recognition
• Video Input
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Audio-Visual (Multimedia) Input Devices - Microphones and Speech Recognition
• Microphones can accept auditory input. A microphone requires a sound card in the PC.
• A sound card can digitize analog sound signals, and convert digital sound signals to analog form.
• With speech recognition software, you can use your microphone to dictate text, navigate programs, and choose commands.
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Microphones
Sound Card
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Audio-Visual (Multimedia) Input Devices – Video Input
• PC video cameras digitize full-motion images.
• Digital cameras capture still images.
• These cameras break images into pixels and store data about each pixel.
• Video images may be compressed to use less memory and storage space.
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Digital Cameras
Camcorder
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Input Devices Summary
Keyboard Mouse
Variants of Mouse Trackballs Track pad Integrated Pointing Device
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Alternate Input DeviceHand Devices
Pen Touch Screen Game Controllers
JoystickGame pad
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Optical Input Devices Bar Code Image Scanners and OCR
Hand-held scannerPage scannerDocument scannerContinuous scannerOptical Mark scanner Iris/Retina scannerSignature scannerFinger print scannerPalm scanner
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Audio-Visual Input DevicesMicrophones and Speech RecognitionVideo Input
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Output Device
A device that allows a computer to communicate with
the user by displaying processed data in a way the
user can understand and use.
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The Monitors - a television – like display for softcopy output in a computer system
Categories of Monitors Monitors are categorized by the technology they use:
• Cathode ray tube (CRT) monitors
• Flat-panel displays And by the way they display colors:
• Monochrome – One color on a black background
• Grayscale – Shades of gray on a white or off-white background
• Color – From 16 to 16 million unique colors
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Monochrome
Grayscale
Colored
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Monitors - CRT Monitors
• In CRT monitors, electrons are fired at phosphor dots on the screen.
• The dots are grouped into pixels, which glow when struck by electrons.
• In color CRTs, each pixel contains a red, green, and blue dot. These glow at varying intensities to produce color images.
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Monitors - Flat-Panel Monitors
• Most flat-panel monitors use liquid crystal display (LCD) technology.
• Passive matrix LCD uses a transistor for each row and column of pixels.
• Active matrix LCD uses a transistor for each pixel on the screen.
• Thin-film transistor displays use multiple transistors for each pixel.
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Flat-panel monitors take up less desk space.
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DTV – Digital Television
A digital signal transmits the information for video and sound as ones and zeros instead of as a wave.
DTV usually uses MPEG-2 encoding, the industry standard for most DVDs, to compress the signal to a reasonable size.
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The picture, even when displayed on a small TV, is better quality.
A digital signal can support a higher resolution, so the picture will still look good when shown on a larger TV screen.
The video can be progressive rather than interlaced - the screen shows the entire picture for every frame instead of every other line of pixels.
TV stations can broadcast several signals using the same bandwidth. This is called multicasting.
If broadcasters choose to, they can include interactive content or additional information with the DTV signal.
It can support high-definition (HDTV) broadcasts.
DTV has several advantages:
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part of the DTV transition The highest HDTV resolution is 1920 x 1080
pixels. HDTV can display about ten times as many pixels as an analog TV set.
HDTV – High Definition TV
HDTV requires three parts: A source, such as a local, cable or satellite
HDTV station A way to receive the signal, like an antenna,
cable or satellite service An HDTV set
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HDTVs don't have to be enormous. This 26-inch set is HDTV ready.
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If you purchase an HDTV-ready set, you'll need a receiver before you can watch high-definition
broadcasts.
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EDTV isn't one of the digital broadcast formats - it's a description of the level of picture quality the set can produce. An EDTV set can produce better quality than SDTV, but it's not an HDTV set. Most EDTV sets are flat-panel LCD or plasma sets.
EDTV – Enhanced Definition TV
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PC Projectors
• A PC projector connects to a PC and is used to project images on a large screen.
• Many PC projectors provide the same resolutions and color levels as high-quality monitors.
• Digital light processing (DLP) projectors use a microchip containing tiny mirrors to produce very sharp, bright images.
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Projected Screen
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Printers fall into two categories:
• Impact printers use a device to strike an inked ribbon, pressing ink from the ribbon onto the paper.
• Non-impact printers use different methods to place ink (or another substance) on the page.
The Printers
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Evaluating Printers
When evaluating printers, consider four criteria:
• Image quality – Measured in dots per inch (dpi). Most printers produce 300 – 600 dpi.
• Speed – Measured in pages per minute (ppm) or characters per second (cps).
• Initial cost – Consumer printers cost $250 or less, but professional printers can cost thousands of dollars.
• Cost of operation – This refers to the cost of supplies used by the printer.
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Dot Matrix Printers
• How Do Dot Matrix Printers Work?
• Performance
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Dot Matrix Printers -How Do Dot Matrix Printers Work?
• Dot matrix printers are a common type of impact printer.
• A dot matrix printer's print head contains a cluster of pins. The printer can push the pins out to form patterns in rapid sequence.
• The pins press an inked ribbon against the paper, creating an image.
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Dot Matrix Printers - Performance
• Lower-resolution dot matrix printers use nine pins. Higher-resolution models have 24 pins.
• Speed is measured in characters per second (cps). Some dot matrix printers print 500 cps.
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Ink Jet Printers
• How Do Ink Jet Printers Work?
• Performance
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Ink Jet Printers – How Do Ink Jet Printers Work?
• Ink jet printers are an example of non-impact printers.
• The printer sprays tiny droplets of ink onto the paper.
• Ink jet printers are available for color and black-and-white printing.
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Ink Jet Printers - Performance
• Ink jet printers offer speeds of (2 – 4 pages per minute ppm) and resolution (300 – 600 dots per inch dpi), comparable to low-end laser printers.
• Ink jet printers are inexpensive and have low operating costs.
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Laser Printers
• How Do Laser Printers Work?
• Performance
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Laser Printers – How Do Laser Printers Work?
• Laser printers are non-impact printers.
• They use heat and pressure to bond particles of toner to paper.
• Laser printers are available for color and black-and-white printing.
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Laser Printers - Performance
• Laser printers provide resolutions from 300 – 1200 dpi and higher.
• Black-and-white laser printers usually produce 4 – 16 ppm.
• Laser printers produce higher-quality print than ink jet printers, but are more expensive.
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Snapshot Printers
•Snapshot printers are specialized, small-format printers that print digital photographs.
•Snapshot printers are fairly slow, and can be more expensive to operate
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Snapshot printers are popular among digital camera users
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Other High-Quality Printers
Print shops and publishers use these printers to create high-quality color images:
Fiery
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Other High-Quality Printers
Thermal-wax printer Thermal-wax ribbons
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Other High-Quality Printers
Dye Sublimation
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Other High-Quality Printers
IRIS Printers
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Other High-Quality Printers
Plotters
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Plotters use mechanical, ink jet, or thermal technology to create large-format images for architectural or engineering uses.
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MonitorUse
CRT Flat-panel
Color Monochrome Grayscale Colored
PC Projector
Output Devices Summary
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PrinterCategories
ImpactType WriterDot Matrix
Non-ImpactLaserInkjetThermal WaxOther High Quality Printers
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Storage Devices
A device from which the computer reads data, and to which the
computer writes data.
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Storage Devices Summary
Magnetic DevicesFloppy DiskHard DiskMagnetic TapeDisk Cartriages
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Optical Storage DevicesCompact Disk Read-Only Memory (CD-ROM)Digital Video Disk Read-Only Memory (DVD-
ROM)CD-Recordable (CD-R)CD-Rewritable (CD-RW)PhotoCD
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Other Removable Storage DevicesUSB Flash DriveCompact FlashMemory StickSmart Media
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Categorizing Storage Devices
• The physical material that actually holds data is called a storage medium. The surface of a floppy disk is a storage medium.
• The hardware that writes data to or reads data from a storage medium is called a storage device. A floppy disk drive is a storage device.
• The two primary storage technologies are magnetic and optical.
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Magnetic Storage Devices
• Diskettes
• Hard Disks
• Other Magnetic Storage Devices
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Early Storage Device
some early computers used paper punch cards to store information
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Magnetic Storage Devices
• A magnetic disk's medium contains iron particles, which can be polarized—given a magnetic charge—in one of two directions.
• Each particle's direction represents a 1 (on) or 0 (off), representing each bit of data that the CPU can recognize.
• A disk drive uses read/write heads containing electromagnets to create magnetic charges on the medium.
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Random particles(no data stored)
Current flow(write operation)
Organized particles(represent data)
Medium
Write head
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As the mediumrotates, the headwrites the data.
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Magnetic Storage Devices - Formatting
• Before a magnetic disk can be used, it must be formatted—a process that maps the disk's surface and determines how data will be stored.
• During formatting, the drive creates circular tracks around the disk's surface, then divides each track into sectors.
• The OS organizes sectors into groups, called clusters, then tracks each file's location according to the clusters it occupies.
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Formatted Disk
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Magnetic Storage Devices - Disk Areas
When a disk is formatted, the OS creates fourareas on its surface:
• Boot sector – stores the master boot record, a small program that runs when you first start (boot) the computer
• File allocation table (FAT) – a log that records each file's location and each sector's status
• Root folder – enables the user to store data on the disk in a logical way
• Data area – the portion of the disk that actually holds data
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Diskettes
• Diskette drives, also known as floppy disk drives, read and write to diskettes (called floppy disks or floppies).
• Diskettes are used to transfer files between computers, as a means for distributing software, and as a backup medium.
• Diskettes come in two sizes: 5.25-inch and 3.5-inch.
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5.25-inch3.5-inch
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3.5 inchfloppy
and drive
149Floppy Disk Drive
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Hard Disks
• Hard disks use multiple platters, stacked on a spindle. Each platter has two read/write heads, one for each side.
• Hard disks use higher-quality media and a faster rotational speed than diskettes.
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Read/write heads
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Removable hard disks combine high capacity with the convenience of diskettes.
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Disk Capacities
• Diskettes are available in different capacities, but the most common store 1.44 MB.
• Hard disks store large amounts of data. New PCs feature hard disks with capacities of 10 GB and higher.
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Other Magnetic Storage Devices
• High-capacity floppy disks offer capacities up to 250 MB and the portability of standard floppy disks.
• Disk cartridges are like small removable hard disks, and can store up to 2 GB.
• Magnetic tape systems offer very slow data access, but provide large capacities and low cost.
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Magnetic Tape
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Due to long access times, tapedrives are used mainly for backups.
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The primary types of optical storage are:
• CD• CD-Recordable (CD-R) • CD-Rewritable (CD-RW)
• DVD• CD-Recordable (CD-R) • CD-Rewritable (CD-RW)
• PhotoCD
• Blu-ray Disc (BD)
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How Optical Storage Works
• An optical disk is a high-capacity storage medium. An optical drive uses reflected light to read data.
• To store data, the disk's metal surface is covered with tiny dents (pits) and flat spots (lands), which cause light to be reflected differently.
• When an optical drive shines light into a pit, the light cannot be reflected back. This represents a bit value of 0 (off). A land reflects light back to its source, representing a bit value of 1 (on).
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1 0
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CD-ROM
• In PCs, the most commonly used optical storage technology is called Compact Disk Read-Only Memory (CD-ROM).
• A standard CD-ROM disk can store up to 650 MB of data, or about 70 minutes of audio.
• Once data is written to a standard CD-ROM disk, the data cannot be altered or overwritten.
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CD-ROM Speeds and Uses
• Early CD-ROM drives were called single speed, and read data at a rate of 150 KBps. (Hard disks transfer data at rates of 5 – 15 MBps).
• CD-ROM drives now can transfer data at speeds of up to 7800 KBps. Data transfer speeds are getting faster.
• CD-ROM is typically used to store software programs. CDs can store audio and video data, as well as text and program instructions.
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DVD-ROM
• A variation of CD-ROM is called Digital Video Disk Read-Only Memory (DVD-ROM), and is being used in place of CD-ROM in many newer PCs.
• Standard DVD disks store up to 9.4 GB of data—enough to store an entire movie. Dual-layer DVD disks can store up to 17 GB.
• DVD disks can store so much data because both sides of the disk are used, along with sophisticated data compression technologies.
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Other Optical Storage Devices
• A CD-Recordable (CD-R) drive lets you record your own CDs, but data cannot be overwritten once it is recorded to the disk.
• A CD-Rewritable (CD-RW) drive lets you record a CD, then write new data over the already recorded data.
• PhotoCD technology is used to store digital photographs.
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BLU-RAY DISC
The new format offers an immense storage capacity (up to 50GB) that is perfect for High Definition video recording and distribution, as well as for storing large amounts of data.
A single-layer Blu-ray disc, which is roughly the same size as a DVD, can hold up to 27 GB of data -- that's more than two hours of high-definition video or about 13 hours of standard video.
A double-layer Blu-ray disc can store up to 54 GB, enough to hold about 4.5 hours of high-definition video or more than 20 hours of standard video.
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Photo courtesy Blu-ray Disc Association
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Other Removable Storage Devices
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Memory stick, Flash Memory, Compact Flash, Smart Media, Secure Digital, Micro Drive.
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Smart Media Card
A removable flash memory card that can be used in several different types of digital devices; including digital cameras, digital music players and digital voice recorders.
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Memory Stick
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The Pen Drive, USB Flash Drive
Pluggable, portable and powerful, USB flash drives, sometimes we call them JumpDrives, Pocket drives, Pen drives, or Thumb drives, are always the best digital storage solution. All USB flash drives pretty much operate the same way. USB flash drives may have different design, different capacity and different price – and some USB flash drives feature add-on functions such as MP3 players – but they do share some other characteristics:
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With proper use, an USB flash drive can last more than 10 years.
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Other Removable Storage Devices
Secure Digital
Compact flash
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Other Removable Storage Devices
Iomega Peerless
Zip Drive
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Communication Devices
Perform both input and output, allowing computers to share
information.
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Modem The word "modem" is a contraction of the words
modulator-demodulator. A modem is typically used to send digital data over a phone line.
The sending modem modulates the data into a signal that is compatible with the phone line, and the receiving modem demodulates the signal back into digital data. Wireless modems convert digital data into radio signals and back.
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Modem converts digital signals into analog signals so that the data can be transmitted over the telephone lines
* Telephone lines were designated for voice communication, not data communication
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56k Internal Modem
External Modem
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HeadsetHeadset consists of a receiver (speaker) that lets
you hear the person at the other end of the conversation, and a transmitter (microphone) that converts your voice into electrical impulses to be transmitted to the other person.
In a headset, these two components are usually supported by a headband over your head) or an earhook (over your ear), or something in your ear like a hearing aid or a stethoscope. Most modern headsets are comfortable for people who wear eyeglasses.
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A good headset can give you extremely good sound for games, movies and music without disturbing others; and the microphone works great for speech recognition programs and internet phone calls
If you travel with a laptop computer, a headset can provide much better sound than the tiny built-in speakers; and it's much easier to pack a headset than to stuff speakers into your computer case.
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Network Interface Card (NIC)NIC facilitates and controls the exchange of data
between/among the micros in a network.
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WebCam A simple Webcam consists of a digital
camera attached to your computer. They are easy to connect through a USB port (earlier cameras connected through a dedicated card or the parallel port).
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In order for you to create a simple Webcam, you need three things:
A camera of some sort connected to your computer
A piece of software that can grab a frame from the camera periodically
A relatively consistent connection between your computer and the Internet.
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Software
A set of electronic instructions that tells the computer how to do certain tasks. A set of
instructions is often called a program.
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• When a computer is using a particular program, it is said to be running or executing the program.
• The two most common types of programs are system software and application software.
The Parts of a Computer System - Software
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• Software – also called programs – consists of organized sets of instructions for controlling the computer.
• Some programs exist for the computer's use, to help it manage its own tasks and devices.
• Other programs exist for the user, and enable the computer to perform tasks for you, such as creating documents.
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• System software exists primarily for the computer itself, to help the computer perform specific functions.
• One major type of system software is the operating system (OS). All computers require an operating system.
• The OS tells the computer how to interact with the user and its own devices.
• Common operating systems include Windows,
the Macintosh OS, OS/2, and UNIX .
System Software
TWO BASIC TYPES OF SOFTWARE
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• Application software tells the computer how to accomplish tasks the user requires, such as creating a document or editing a graphic image.
• Some important kinds of application software are:
Word processing programs Spreadsheet softwareDatabase management Presentation programsGraphics programs Networking software Web design tools and browsers Internet applicationsCommunications programs UtilitiesEntertainment and education Multimedia authoring
Applications Software
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Data
Consists of raw facts, which the computer can manipulate and process into information that is
useful to people.
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• Computerized data is digital, meaning that it has been reduced to digits, or numbers. The computer stores and reads all data as numbers.
• Although computers use data in digital form, they convert data into forms that people can understand, such as text, numerals, sounds, and images.
The Parts of a Computer System - Data
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Ten differentsymbols inthe decimalsystem
Numbers above 9 use more than 1 digit
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Users
People are the computer's operators, or users.
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• Some types of computers can operate
without much intervention from people, but personal computers are designed specifically for use by people.
The Parts of a Computer System – Users