Computer Hardware Chapter 3 McGraw-Hill/Irwin Copyright © 2010 by the McGraw-Hill Companies, Inc. All rights reserved.

Learning Objectives Understand the history and evolution of computer hardware Identify the major types and uses of microcomputer, midrange, and mainframe computer systems Outline the major technologies and uses of computer peripherals for input, output, and storage

Learning Objectives Identify and give examples of the components and functions of a computer system Identify the computer systems and peripherals you would acquire or recommend for a business of your choice, and explain the reasons for your selection

Pre-Computer Calculations Counting on fingers and toes Stone or bead abacus Calculate comes from calculus, the Latin word for small stone 1642: first mechanical adding machine Invented by Blasé Pascal, wheels moved counters Modified in 1674 by Von Leibnitz

Pre-Computer Calculations

Pre-Computer Calculations Age of industrialization Mechanical loom used punch cards Above left: Punch card reader. Above right: Punch card writer

Early Computing 19th Century 1880s Charles Babbage proposed the Analytical Engine, which could calculate, store values in memory, perform logical comparisons Never built due to of lack of electronics 1880s Hollerith’s punched cards used to record census data using On/Off patterns – representing digits and letters. The holes turned sensors On or Off when run through tabulating machine This company became the foundation for IBM

Electronic Computers 1946 - First Generation Computer ENIAC (Electronic Numerical Integrator and Computer ) Programmable 5000 calculations per second Used vacuum tubes Drawbacks were size and processing ability (140 square meters)

ENIAC

Electronic Computers 1950s ENIAC replaced by UNIVAC 1, then IBM 704 Calculations jumped to 100,000 per second

Waves of Computing Late 1950s - Second Generation Transistors replaced vacuum tubes 200,000 to 250,000 calculations per second

Waves of Computing Mid-1960s - Third Generation Integrated circuitry and miniaturization 1971 - Fourth Generation Further miniaturization, multiprogramming, virtual storage 1980s - Fifth Generation Millions of calculations per second

Microcomputers 1975 1977 ALTAIR, programmed by flicking switches Commodore & Radio Shack produce PCs

Microcomputers 1979 1982 Apple computer, the fastest selling PC. IBM introduced the PC, which changed the market

Categories of Computer Systems

Microcomputer Systems Called a personal computer or PC Computing power now exceeds that of the mainframes of previous generations Relatively inexpensive Networked professional workstations used by businesses Hand-held, notebook, laptop, tablet, portable, desktop, and floor-standing

Microcomputer Systems

Microcomputer Systems Apollo 11 spacecraft Today's computers Apollo 11 spacecraft 4 GHz 2.048 MHz CPU 1 Pound 70 Pounds

Recommended PC Features

Microcomputer Uses Workstations Network Servers Supports heavy mathematical computer and graphics display demands CAD, investment, and portfolio analysis Network Servers More powerful than workstations Coordinates telecommunications and resource sharing Supports small networks (LAN)and Internet or intranet websites

Workstations Genetic image analysis workstation Example CAD

Microcomputer Uses Terminals Types Any device that allows access to a computer Types Dumb Network (Windows or Internet) Intelligent Transaction Dumb terminals: limited \ no processing capabilities. Example: Keyboard\ monitor. Intelligent terminals: A computer input/output device with its own memory and logic circuits which can perform certain operations normally carried out by the computer. Also known as smart terminal. Transaction terminals: ex debit card” magnetic strep reader” barcode reader ATM

Terminals

Network Computers Corporate PC Criteria: Solid performance at a reasonable price Operating system ready, from the network servers No or minimal disk storage linked to network Connectivity Security-equipped Low TCO Ease of software distribution and licensing

Information Appliances Hand-held microcomputer devices 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(appointments, to do list) with desktop PCs or servers Latest entrant is the BlackBerry, iPhone PDAs include Video-games

Information Appliances

Midrange Systems High-end network servers that handle large-scale processing of business applications Not as powerful as mainframes Less expensive to buy, operate, maintain Often as a powerful network server used to manage Large Internet websites, intranets, extranets Integrated, enterprise-wide applications First became popular as minicomputers E.g. used in manufacturing plants. Used as front-end servers Assists mainframes with telecommunications and networks

Mainframe Computer Systems Large, fast, powerful computer systems Large primary storage capacity Reduction in acquisition and operating cost (coolers) High transaction processing Handles complex computations E.g. international banks, oil companies Widely used as superservers for… Large client/server networks High-volume Internet websites for large companies Becoming a popular computing platform for… Data mining, warehousing, electronic commerce applications

Mainframes

Super-server

Supercomputer Systems Extremely powerful systems designed for… Scientific, engineering, and business applications Massive numeric computations Markets include… Government research agencies Large universities Major corporations E.g. global weather forecasting Uses parallel processing or (MPP) Billions to trillions of operations per second (gigaflops and teraflops) Price range

Minisupercomputers Use (SMP) symmetric multiprocessing (DSM) distributed shared memory, smaller number of interconnected microprocessors Price range: hundreds of thousands

The Next Wave of Computing Harnessing the infinite amount of unused computing power Desktops and laptops within an organization Distributed or grid computing (opposite to traditional supercomputers) Parallel computing that relies on complete computers connected to a network Harnesses the unused CPU power in all connected computers, even between organizations

Distributed (grid) Computing Advantage: computers can be purchased as a hardware and when combined, produces similar computer resources to a multiprocessor supercomputer Significantly cheaper Can be formed from computing resources belonging to multiple individuals or organizations e.g. SETI

Grid Computing

Distributed (grid) Computing Disadvantage: Computers might not be trustworthy Solution: Assign same work to different nodes Disadvantage: Lack of central control over the hardware, computers might drop out of the network. Solution: Assign work and reduce the need for continuous connectivity. Reassign work when no result is reported.

Computer System Concept Input Control System of hardware devices organized by function Processing Storage Output

Computer System Concept

Computer Processing Speeds Early computers Milliseconds (thousandths of a second) Microseconds (millionths of a second) Current computers Nanoseconds (billionth of a second) E.g. person Picoseconds (trillionth of a second) Program instruction processing speeds Million instructions per second (MIPS) Megahertz (millions of cycles per second) Gigahertz (billions of cycles per second) Commonly called “clock speed”

Computer Processing Speeds Throughput 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 microprocessors, such as math coprocessor

Moore’s Law Originally observed in 1965, Moore’s Law holds true today Common corollary of Moore’s Law… Computing prices will be cut in half every 18 to 24 months This has been consistently accurate Applies to cost of storage as well Doubling of the number of transistors per integrated circuit every 18 to 24 months

Moore’s Law Can computers get any faster? Can we afford the computers of the future? The price of a given level of computing power will be cut in half approximately every 18 to 24 months It is useful in understanding where we have been and where are we going This caused marketing and engineering departments of semiconductor manufacturers to focus on the increase in processing power. The improvement in hardware does not mean improvement in the software.

Computer Peripherals: Input, output, and storage technology

Peripherals Peripheral Generic name for all input, output, and secondary storage devices Parts of the computer system (not the CPU) 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

Peripherals Advice

Input Technologies Common input devices Keyboard Graphical User Interface (GUI) Electronic mouse and trackball Pointing stick Touchpad Touch screen

Input technologies Keyboard: most widely-used Graphical user interface (GUI) Icons, menus, windows, buttons, bars Used for selection Trend to natural user interface as opposed to paper source documents

Pointing Devices Electronic Mouse Trackball – Stationary device like a mouse Roller ball used to move cursor on screen. Pointing Stick – Small eraser head-like device in keypad Moves cursor in direction of pressure placed on stick.

Pointing Devices Touchpad – Small rectangular touch-sensitive surface Moves the cursor in the direction of finger moves on the pad Touch Screen – use computer by touching screen Video display screen that emits a grid of infrared beams, sound waves, or a slight electric current Grid is broken when the screen is touched.

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

Speech Recognition Systems Speech may be the future of data entry Easiest, most natural means of human communication Recognizing speech patterns Discrete, requires pauses between each word Continuous speech recognition software (CSR) recognizes continuous, conversationally paced speech

Speech Recognition Software Speech recognition systems digitize, analyze, and classify speech and sound patterns Compares to a database of sound patterns Passes recognized words to software Typically requires voice recognition training Speaker-independent systems Allow computers to recognize words from a voice never heard before Typically used in voice-messaging computers

Optical Scanning Devices read text or graphics and convert them into digital computer input Enables direct entry of data from source documents Document management library system Scans documents, then organizes and stores them for easy reference or retrieval

Optical Scanning Scanners Optical Character Recognition (OCR) Compact desktop models are popular for low cost and ease of use Larger, more expensive flatbed scanners are faster, offer high-resolution color scanning Optical Character Recognition (OCR) Software that reads characters and codes Used to read merchandise tags, sort mail, score tests, read bar codes

Other Input Technologies Magnetic Stripe Smart Cards Digital Cameras Magnetic Stripe Reads the magnetic stripe on credit cards Smart Cards Microprocessor chip and memory on credit card Used more in Europe than in the U.S. Digital Cameras Allows you to shoot, store, and download photos or full-motion video with audio into a PC Images and audio can then be edited or enhanced Magnetic Ink Character Recognition (MICR) Identification numbers of bank and account printed in magnetic ink on bottom of check 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 Magnetic Ink Character Recognition (MICR)

Output Technologies Voice Response Video Displays Printed Output Increasingly found along with video displays in business applications Video Displays Cathode-ray tube (CRT) Liquid crystal display (LCD) Plasma displays (TVs, flat-panel monitors) Printed Output Inkjet and laser

Storage Tradeoffs Storage media cost, speed, and capacity tradeoffs. Cost increases with faster access speeds but decreases with increased capacity.

Computer Storage Fundamentals Uses two-state (binary) data representation On (1) or Off (0) Data processed & stored in computer systems through On/Off signals Bit Smallest element of data Either zero or one Binary representation Data are processed and stored in computer system through the presence or absence of signals Either ON or OFF ON = number 1 OFF = number 0 Bit (short for binary digit) Smallest element of data Either zero or one the capacity of memory chips is represented in bits Byte Group of eight bits which operate as a single unit Represents one character or number Group of eight bits, which operate as a single unit Byte Represents one character or number

Representing Characters in Bytes

Storage Capacity Measurement Kilobyte (KB) One thousand bytes Megabyte (MB) One million bytes Gigabyte (GB) One billion bytes Terabyte (TB) One trillion bytes Petabyte (PB) One quadrillion bytes

Direct (Random) and Sequential Access

Direct Access Direct or Random Access Also called random access. Directly store and retrieve data Each storage position has: a unique address can be accessed in the same length of time Represent primary storage devices such as: Semiconductor memory chips, magnetic disks.

Sequential Access Sequential Access Data is stored and retrieved sequentially Must be accessed in sequence by searching through prior data Media such as: Magnetic tape known as sequential access devices.

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) Read-Only Memory (ROM) 1. Most widely used primary storage medium 2. Volatile memory 3. Read/write memory 1. Permanent storage “nonvolatile” 2. Can be read, but not overwritten 3. Frequently used programs burnt into chips during manufacturing 4. Called firmware

Flash Drives Sometimes called a jump drive Uses a small chip containing thousands of transistors Can store data for virtually unlimited periods without power Easily transported Highly durable Storage capacity of up to 20 GB Plugs into any USB port

Hard Disk Drives & Floppy Disks (diskettes) Magnetic Disks Hard Disk Drives & Floppy Disks (diskettes) 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 The design allow for higher speed, greater data recording, more tolerance. Fixed or removable Capacity from several hundred MBs to hundreds of GBs Used for secondary storage Fast access and high capacity Reasonable cost

RAID Storage Redundant Arrays of Independent Disks Provides virtually unlimited online storage 6 to more than 100 hard disk drives are combined into a single unit Data is 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 storage Tape reels, cassettes, and cartridges Used in robotic, automated drive assemblies Archival and backup storage Lower-cost storage solution

Optical Disks

Uses of Optical Disks Long-term storage of historical image files Image Processing Long-term storage of historical image files Storage of scanned documents Publishing Medium Allows fast access to reference materials Catalogs, directories, and so on Interactive Multimedia Applications Video games, educational videos, and so on

Radio Frequency Identification (RFID) One of the newest, 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 Passive chips derive power from reader signal Active chips are self-powered

RFID Versus Bar Coding Scans from greater distance RFID Can store data Privacy Concerns Invisible nature of the system Capacity to transmit fairly sophisticated messages