chapter 3

Peripherals

- Peripheral is a generic name for all input, output, and secondary storage devices Parts of the computer system, but not the CPU Are all online devices - Online devices Separate from the CPU, but electronically connected to and controlled by it - Offline devices Separate from and not under the control of the CPU

Corporate PC Criteria

- Solid performance at a reasonable price - Operating system ready - Connectivity - Network interface cards or wireless capabilities

Speech Recognition Systems

- Speech be the future of data entry Easiest, most natural means of human communication - Recognizing speech patterns Discrete required pauses between each word Continuous speech recognition software (CSR) recognized continuous, conversationally paced speech - Speech recognition systems digitize, analyze, and classify speech and sound patterns Compares to a database of sound patterns in its vocabulary Passes recognized words to the application software Typically requires voice recognition training - Speaker-independent voice recognition systems Allows computer to recognize words from a voice it has never heard before Typically used in voice-messaging computers

Magnetic Disks

- Used for secondary storage Fast access and high capacity Reasonable cost - Types of Magnetic Disks Floppy Disks (diskettes) -Magnetic disk inside a plastic jacket Hard Disk Drives (hard drives) - Magnetic disk, access arms, and read/write heads in sealed module for stable environment - Fixed or removable - Capacity from several hundred MBs to hundreds of GBs

Microcomputer Systems

- Usually called a personal computer or PC - Computing power now exceeds that of the mainframes of previous generations - Relatively inexpensive - Are the networked professional workstations used by business processions - Versions include hand-held, notebook, laptop, tablet, portable, desktop, and floor-standing

Optical Scanning

1- Devices read text or graphics and convert them into digital input for a computers Enables direct entry of data from source documents A document management library system Scans documents, then organizes and stores them for easy reference or retrieval 2- Scanners Compact desktop models are popular for low cost and ease of use Larger, more expensive flatbed scanners are faster and provide high-resolution color scanning 4- Optical Character Recognition (OCR) Software that reads characters and codes Used to real merchandise tags, sort mail, score tests Optical scanning wands read bar codes

Computer Processing Speeds

1- Early computers - Milliseconds (thousandths of a second) - Microseconds (millionths of a second) 2- Current computers - Nanoseconds (billionth of a second) - Picoseconds (trillionth of a second) 3- Program instruction processing speeds - Megahertz (millions of cycles per second) - Gigahertz (billions of cycles per second) Commonly called the "clock speed"

Supercomputer Systems

1- Extremely powerful systems designed for... - Scientific, engineering, and business applications - Massive numeric computations 2- Markets include... - Government research agencies - Large universities - Major corporations 3- Uses parallel processing - Billions to trillions of operations per second (gigaflops and teraflops) - Costs $5 to $50 million

Information Appliances

1- Hand-held microcomputer devices 2- Known as personal digital assistants (PDAs) - Web-enabled PDAs use touch screens, handwriting recognition, or keypads - Mobile workers use to access email or the Web, exchange data with desktop PCs or servers - Latest entrant is the BlackBerry 3- PDAs include - Video-game consoles - Cellular and PCS phones - Telephone-based home email appliances

Midrange Systems

1- High-end network servers that handle large-scale processing of business applications 2- Not as powerful as mainframes -Less expensive to buy, operate, and maintain 3- Often used to manage - Large Internet websites - Corporate intranets and extranets - Integrated, enterprise-wide applications 4- Used as front-end servers to assist mainframes with telecommunications and networks

Uses of Optical Disks

1- Image processing - Long-term storage of historical image files - Storage of scanned documents 2- Publishing medium - Allows fast access to reference materials -Catalogs, directories, and so on 3- Interactive multimedia applications -Video games, educational videos, and so on

Mainframe Computer Systems

1- Large, fast, powerful computer systems - Large primary storage capacity - High transaction processing - Handles complex computations 2- Widely used as superservers for... - Large client/server networks - High-volume Internet websites 3- Becoming a popular computing platform for... - Data mining and warehousing - Electronic commerce applications

Other Input Technologies

1- Magnetic Stripe Reads the magnetic stripe on credit cards 2- Smart Cards Microprocessor chip and memory on credit card Use more in Europe than in the U.S. 3- Digital Cameras Allows you to shoot, store, and download photos or full-motion video with audio into the PC Images and audio can then be edited or enhanced 3-Magnetic Ink Character Recognition (MICR) Used by banks to magnetically read checks and deposit slips Requires an iron oxide-based ink Reader-sorter equipment magnetizes the ink, then passes it under a reading head to sense the signal

Radio Frequency Identification (RFID)

1- One of the newest and fastest growing storage technologies - System for tagging and identifying mobile objects - Used with store merchandise, postal packages, casino chips, pets - Special reader allows objects to be tracked as they move from place to place - Chips half the size of a grain of sand 2- Passive chips derive power from reader signal Active chips are self-powered

Computer Storage Fundamentals

1- Uses a two-state or binary representation of data On or Off On represents the number 1 Off represents the number 0 2- Data are processed and stored in computer systems through the presence or absence of On/Off signals

Output Technologies

1- Video Displays Cathode-ray tube (CRT) Liquid crystal displays (LCDs) Active matrix and dual scan Plasma displays Used in large TVs and flat-panel monitors 2- Printed Output Inkjet printers spray ink on a page Laser printers use an electrostatic process similar to a photocopying machine

Microcomputer Uses

1- Workstations - Supports have mathematical computer and graphics display demands - CAD, investment and portfoliogroup analysis 2- Network Servers - More powerful than workstations - Coordinates telecommunications and resource sharing - Supports small networks and Internet or intranet websites

Computer System Concept

A system of hardware devices organized by function Input - Keyboards, touch screens, pens, electronic mice, optical scanners - Converts data into electronic form for entry into computer system Processing - Central Processing Unit (CPU) - CPU subunits: arithmetic-logic and control unit Output - Video display units, printers, audio response units, and so on - Converts electronic information into human- intelligible form Storage - Primary storage (memory) - Secondary storage (disk drives) Control - CPU controls other components of the system

Bit and Byte

Bit Short for binary digit Smallest element of data Either zero or one Byte Group of eight bits, which operate as a single unit Represents one character or number

Input Technologies

Keyboard - Still most widely used input device Graphical User Interface (GUI) - Icons, menus, windows, buttons, bars; Selected with pointing devices Electronic Mouse - Most popular pointing device; Pressing mouse buttons initiates activity represented by the icon selected Trackball - Stationary device, similar to mouse; Roller ball moves cursor on screen Pointing Stick - Small eraser-head device embedded in keyboard; Cursor moves in the direction of the pressure placed on the stick Touchpad - Small, rectangular, touch-sensitive surface - Usually on keyboard - Cursor moves in direction your finger moves Touch Screen Use computer by touching screen Screen emits a grid of infrared beams, sound waves, or electric current Grid is broken when screen is touched

Storage Capacity Measurement

Kilobyte (KB): one thousand bytes Megabyte (MB): one million bytes Gigabyte (GB): one billions bytes Terabyte (TB): one trillion bytes Petabyte (PB): one quadrillion bytes

Semiconductor Memory

Microelectronic semiconductor memory chips are used for primary storage Advantages: small size, fast, shock and temperature resistance Disadvantages: volatility; must have uninterrupted electric power or loses memory

Types of Semiconductor Memory

Random Access Memory (RAM) Most widely used primary storage medium Volatile memory Read/write memory Read-Only Memory (ROM) Permanent storage Can be read, but not overwritten Frequently used programs burnt into chips during manufacturing process Called firmware

RAID Storage

Redundant Arrays of Independent Disks - Disk arrays of hard disk drives - Provides virtually unlimited online storage - Combines from 6 to more than 100 small hard disk drives into a single unit - Data are accessed in parallel over multiple paths from many disks - Redundant storage of data on several disks provides fault-tolerant capacity -Storage area networks can interconnect many RAID units

Magnetic Tape

Secondary storagetape (used in recording sound, pictures, or computer data) . Tape reels, cassettes, and cartridges Used in robotic, automated drive assemblies Archival and backup storage Lower-cost storage solution

Flash Drives

Sometimes referred to as a jump drive Uses a small chips containing thousands of transistors Can store data for virtually unlimited periods without power Easily transported and highly durable Storage capacity of up to 1 GB Plugs into any USB port

Computer Processing Speeds(throughput)

Throughput - The ability to perform useful computation or data - processing assignments during a given period Speed is dependant on - Size of circuitry paths (buses) that interconnect microprocessor components - Capacity of instruction processing registers - Use of high-speed cache memory - Use of specialized microprocessor, such as math coprocessor

Pen-Based Computing

Used in Tablet PCs and PDAs - Pressure-sensitive layer, similar to touch screen, under liquid crystal display screen -Software digitizes handwriting, hand printing, and hand drawing