Computers Are Your Future © 2005 Prentice-Hall, Inc.

Computers Are Your Future Chapter 5 Input/Output and Storage © 200 Prentice-Hall, Inc

What You Will Learn About The purpose of special keys and the most frequently used pointing devices Input devices used to get audio and digital data into the computer The characteristics of a monitor’s quality and the various types of monitors The two major types of printers The difference between memory and storage © 200 Prentice-Hall, Inc

What You Will Learn About The categories of storage devices The performance characteristics of hard drives How data is stored on both hard and floppy disks The various optical storage media available for personal computers © 200 Prentice-Hall, Inc

Input Input is any data entered into the computer’s memory. Types of input include: Data – Unorganized information (words, numbers, images, or sounds) that the computer converts to meaningful information Software – Programs transferred from storage devices to the computer’s memory Commands – Instructions that tell the computer what to do Responses – Prompts requiring user feedback © 200 Prentice-Hall, Inc

Input Devices: Giving Commands Keyboard Mouse Other Pointing Devices © 200 Prentice-Hall, Inc

Keyboard The keyboard allows the computer user to enter words, numbers, punctuation, symbols, and special function commands into the computer’s memory. © 200 Prentice-Hall, Inc

Types of Keyboards Enhanced / Extended Keyboard Ergonomic Keyboard Enhanced or Extended keyboard – Typically 101 keys laid out in the QWERTY fashion; connected to the computer by a cable Cordless keyboard – Uses infrared or radio wave signals Ergonomic keyboard – Designed to help prevent cumulative trauma disorder (CTD) or damage to nerve tissues in the wrist and hand due to repeated motion © 200 Prentice-Hall, Inc

The Mouse The mouse is the most widely used pointing device. A mouse is palm sized. As the mouse is moved, its movements are mirrored by the on-screen pointer. © 200 Prentice-Hall, Inc

Types of Mice Wheel Mouse Cordless Mouse Wheel mouse – Contains a rotating wheel used to scroll vertically within a text document; connects to PS/2 port or USB port Cordless mouse – Uses infrared signals to connect to the computer’s IrDA port; it must be within sight of the receiving port © 200 Prentice-Hall, Inc

Using the Mouse Mouse buttons enable the user to initiate actions. Clicking (left-, right-, or double-clicking) allows the user to select an item on the screen or open a program or dialog box Click and drag – Holding down the left mouse button and moving the mouse enables the user to move objects on the screen © 200 Prentice-Hall, Inc

Other Types of Pointing Devices Touch Screen Trackball Pointing Stick Joystick Pen Touch Pad © 200 Prentice-Hall, Inc

Audio Input Computers can accept input from a microphone. An expansion card called a sound card records and plays back sound files. Sound files contain digitized sound data. Popular sound file formats include: Windows WAV Moving Pictures Expert Group (MPEG) MP2 and MP3 Musical Instrument Digital Interface (MIDI) © 200 Prentice-Hall, Inc

Audio Input: Speech Recognition Speech recognition is a type of input in which the computer recognizes words spoken into a microphone. Special software and a microphone are required. Latest technology uses continuous speech recognition where the user does not have to pause between words. © 200 Prentice-Hall, Inc

Digital Input: Digital Cameras and Digital Video Click on the picture to play the video. © 200 Prentice-Hall, Inc

Alternative Input Devices Fax Machines Scanners Flatbed Barcode reader © 200 Prentice-Hall, Inc

Digital Cameras The image’s light falls on a charge-coupled device (CCD) which transforms the light’s patterns into pixels (individual dots). Images are stored in the camera using flash memory. The most popular types are CompactFlash and SmartMedia. Photo-editing programs enable the user to edit the images. © 200 Prentice-Hall, Inc

Digital Video A video capture board transforms analog video into digital video. Digital video cameras use digital technologies to record video images. A Web cam is a low resolution video camera. Digital video camera Web cam © 200 Prentice-Hall, Inc

Output Devices: Engaging our Senses Output devices are peripheral devices that enable us to view or hear the computer’s processed data. Visual output – Text, graphics, and video Audio output – Sounds, music, and synthesized speech © 200 Prentice-Hall, Inc

Monitors CRT LCD A monitor is a peripheral device which displays computer output on a screen. Screen output is referred to as soft copy. Types of monitors: Cathode-ray tube (CRT) Liquid Crystal Display (LCD or flat-panel) © 200 Prentice-Hall, Inc

Cathode-ray tube (CRT) Resemble televisions Use picture tube technology Less expensive than a LCD monitor Take up more desk space and use more energy than LCD monitors © 200 Prentice-Hall, Inc

Liquid Crystal Display (LCD) Cells sandwiched between two transparent layers form images Used for notebook computers, PDAs, cellular phones, and personal computers More expensive than a CRT monitor Take up less desk space and use less energy than CRT monitors Types of LCD monitors: Passive-matrix LCD Active-matrix LCD Gas plasma display Field emission display © 200 Prentice-Hall, Inc

Monitor Specifications Screen size – The diagonal measurement of the screen surface in inches (15, 17, 19, 21) Resolution – The sharpness of the image determined by the number of horizontal and vertical dots (pixels) that the screen can display (800 x 600, 1024 x 768, 1600 x 1200) Refresh rate – The speed at which the screen is redrawn (refreshed) and measured in Hertz (Hz) (60Hz, 75Hz) © 200 Prentice-Hall, Inc

Printers A printer is a peripheral device that produces a physical copy or hard copy of the computer’s output. © 200 Prentice-Hall, Inc

Types of Printers Laser Inkjet Inkjet printer, also called a bubble-jet, makes characters by inserting dots of ink onto paper Letter-quality printouts Cost of printer is inexpensive but ink is costly Laser printer works like a copier Quality determined by dots per inch (dpi) produced Color printers available Expensive initial costs but cheaper to operate per page © 200 Prentice-Hall, Inc

Plotter A plotter is a printer that uses a pen that moves over a large revolving sheet of paper. It is used in engineering, drafting, map making, and seismology. © 200 Prentice-Hall, Inc

Audio Output: Sound Cards and Speakers Audio output is the ability of the computer to output sound. Two components are needed: Sound card – Plays contents of digitized recordings Speakers – Attach to sound card Click an icon to play music. Click the icon again to stop playing. Try clicking on Cheers while playing music. WMA MIDI MP3 WAV Beethoven 1:15 min Rocky 2:56 min Hornsby 48 sec Cheers 15 sec © 200 Prentice-Hall, Inc

Memory vs. Storage RAM – memory Hard Drive – storage Storage, also known as mass media or auxiliary storage, refers to the various media on which a computer system can store data. Storage devices hold programs and data in units called files. Memory is a temporary workplace where the computer transfers the contents of a file while it is being used. © 200 Prentice-Hall, Inc

Why Is Storage Necessary? Storage devices: Retain data when the computer is turned off Are cheaper than memory Play an important role during startup Are needed for output © 200 Prentice-Hall, Inc

Storage devices are categorized by: The type of operations they perform The method they use to access the information The technology they use Their location in the storage hierarchy Their capacity and speed © 200 Prentice-Hall, Inc

Sequential vs. Random Access Storage Hard Disk – random-access storage Tape Drive – sequential storage Floppy Disk Drive – random-access storage Sequential – Storage devices that read and write data in a serial (one after the other) fashion Random-Access – Storage devices that read and write data without going through a sequence of locations © 200 Prentice-Hall, Inc

Storage Technologies: Magnetic and Optical Optical Storage – CD/DVD drive Magnetic Storage Magnetic – Storage devices use disks or tapes that are coated with magnetically sensitive material Optical – Storage devices that use laser beams to read patterns etched into plastic disks © 200 Prentice-Hall, Inc

Magnetic Disk Storage A disk is formatted; it is divided into tracks and sectors, and a file allocation table (FAT) is created. Track – circular band Sector – pie shaped section Cluster – two or more adjacent sectors FAT – keeps track of specific locations of files Track Sector Cluster © 200 Prentice-Hall, Inc

Optical Disk Storage Disk surface magnified Cross-section of a disk Microscopic indentations called pits scatter the laser beam’s light. A light-sensing device receives no light from the pits. A signal is sent to the computer corresponding to a 0 in the binary system. Flat, reflective areas, called lands, bounce the light back to the light sensing device, which sends a signal corresponding to a 1. © 200 Prentice-Hall, Inc

The Storage Hierarchy The three levels of storage hierarchy are: Online storage – Also called primary storage, it is made up of the storage devices that are actively available to the computer system. User action is not required. Near-online storage – Also called secondary storage, it is not readily available to the computer system. The user performs an action, such as inserting a disk, to make it available. Offline storage – Also called tertiary storage or archival storage, it is not readily available to the computer system. Devices such as tape backup units store data for archival purposes. © 200 Prentice-Hall, Inc

Storage Capacity and Speed Floppy Disk Hard Drive CD ROM / DVD Capacity – CD-ROM 650 MB; DVD 17 GB Access Time – 80 to 800ms Capacity – 720 KB to 1.44 MB Access Time – 100ms Capacity – Up to 80 GB Access Time – 6 to 12ms A storage device’s performance is measured by: Capacity – The number of bytes of data that a device can hold Access Time – The amount of time, in milliseconds (ms), it takes the device to begin reading data © 200 Prentice-Hall, Inc

Hard Disks Hard disks are high-speed, high-capacity storage devices. Platter Read/Write head Hard disks are high-speed, high-capacity storage devices. They contain metal disks called platters. They contain two or more stacked platters with read/write heads for each side. Hard disks can be divided into partitions to enable computers to work with more than one operating system. © 200 Prentice-Hall, Inc

Factors Affecting a Hard Disk’s Performance Seek time or positioning performance – How quickly the read/write head positions itself and begins transferring information. It is measured in milliseconds (ms). Spindle speed or transfer performance – How quickly the drive transfers data. It is measured in rotations per minute (RPM). © 200 Prentice-Hall, Inc

Floppy and Zip Disks and Drives Zip Drive Floppy Drive Click on the picture to see it work. Floppy Disk A disk or diskette is a portable storage medium. High-density floppy disks that are commonly used today store 1.44 MB of data. Disks work with a disk drive. Zip disks store up to 750 MB of data and are not downwardly compatible with floppy disks. © 200 Prentice-Hall, Inc

CD-ROM Discs and Drives CD-ROM stands for Compact Disc-Read Only Memory. CD-ROM drives can not write data to discs. They are capable of storing 650 MB of data. They are used for storing operating systems, large application programs, and multimedia programs. © 200 Prentice-Hall, Inc

CD-R and CD-RW Discs and Recorders Discs can be read and written to Discs can only be written to “once” CD-R drives are capable of reading and writing data CD-RW Discs can be read and written to Discs are erasable Discs can be written to many times CD-RW drives are capable of reading, writing, and erasing data © 200 Prentice-Hall, Inc

DVD-ROM Discs and Drives DVD stands for Digital Video Disc. DVD technology is similar to CD-ROM technology. DVDs are capable of storing up to 17GB of data. The data transfer rate of DVD drives is comparable to that of hard disk drives. DVD-R and DVD-RW drives have the ability to read/write data. © 200 Prentice-Hall, Inc

Solid State Storage Devices Solid state storage devices use nonvolatile memory chips to retain data. They do not have moving parts. They are small, lightweight, reliable, and portable. © 200 Prentice-Hall, Inc

Solid State Storage Devices Smart Card Memory Stick Compact Flash Memory Flash Memory PC Card Micro Drive © 200 Prentice-Hall, Inc

Chapter 5 Summary Input is the software, data, and information that is entered into the computer’s memory. Input devices such as the keyboard, mouse, and trackball enable the user to enter data. A pointing device enables the user to control movements of an on-screen pointer. Speech recognition software enables the user to enter data into a computer by speaking into a microphone. Video and images can be entered into a computer by way of digital cameras, scanners, and fax modems. Monitors enable the user to view the computer’s processed data. The output is known as soft copy. © 200 Prentice-Hall, Inc

Chapter 5 Summary (continued) The two types of monitors are the CRT and the LCD. A monitor’s quality is measured by screen size, resolution, and refresh rate. Printers produce permanent versions (hard copies) of the computer’s output. The two basic types of printers are the inkjet and laser. Memory makes software and data available for the CPU’s use. Storage devices are categorized by: Data access (sequential or random-access) Technology (magnetic, optical, or solid state) Hierarchy (online, near-online, or offline) Operations (read-only or read/write) © 200 Prentice-Hall, Inc

Chapter 5 Summary (continued) A hard disk’s performance is measured by its positioning performance and transfer rate. Optical storage devices include: CD-ROM– Read-only CD-R– Record once CD-RW– Erasable, write repeatedly DVD-ROM– Read-only DVD-R– Read/write Solid state storage devices include: PC cards Flash memory cards Smart cards © 200 Prentice-Hall, Inc