COMPUTER HARDWARE Chapter 3 Lecture-4 / T. NoufAlmujally
Outline Section 1: • History (Homework) • Types of Computer Systems. • The computer System Concept. Section 2: • Peripherals: • Input Technologies. • Output Technologies. • Storage Technologies.
Microcomputer Systems Called a personal computer or PC Computing power now exceeds that of the mainframes of previous generations Relatively inexpensive Desktop, Hand-held, notebook, laptop, tablet, portable, and floor-standing Home , personal , professional , workstation or multiuser systems.
Workstations Network Servers - Supports heavy mathematical computing and graphics display demands Ex: - CAD in engineering,- Portfolio analysis. • - More powerful than workstations • - Coordinates telecommunications and resource sharing • - Supports LAN and Internet. Microcomputer Systems
Terminals • Terminal: is any input/output device connected by a network to a computer. • Types: • Dumb terminals: keyboard and video monitor with limited processing capabilities. • Intelligent terminals: networked PCs that perform data entry and other information processing tasks. • Transaction terminals: • Use keyboards, touch screen, bar code scanners to capture data , while relying on servers in the network for further transaction processing. • ex in banks, ATMs machines, airport check-in, POS.
Terminals • Network terminals: • Windows terminals: depend on network servers for Windows software, processing power and storage. • Internet terminals: depend on the Internet/Intranet servers for their operating systems and application software.
Information Appliances • Hand-held microcomputer devices, known as personal digital assistants (PDAs). • Web-enabled PDAs use touch screens, pen-based handwriting recognition, or keypads. • Mobile workers use to access email or the Web, exchange data with desktop PCs or Web servers. • Latest entrant is the RIM BlackBerry, Apple iPhone. • Information Appliances may also take the form of: • Video-game consoles and other devices that connect to your home television set. Enable you to surf the WWW, email, play. • Telephone-based home appliances that access the web.
Midrange Systems • High-end network servers that handle large-scale processing of business applications. • Not powerful as mainframes. • Less expensive to buy, operate, maintain than mainframes. • First became popular as minicomputers for scientific research and industrial process monitoring. • Today used in: • Computer-aided manufacturing (CAM). • Used as front-end servers to assist mainframes in telecommunications processing and network management.
Mainframe Computer Systems • Large, fast, powerful computer systems • Large primary storage capacity. • High transaction processing • Handles complex computations • Used to: • Handle the information processing of major corporation and government agencies with high transaction processing. • As a superservers for the large client/server networks and high-volume Internet websites for large companies. • Becoming a popular computing platform for: Data mining, warehousing, electronic commerce applications
Supercomputer Systems • Extremely powerful computer systems designed for scientific, engineering and business applications requiring extremely high speeds for massive numeric computations. • Markets for supercomputers include: • Government research agencies. • Large universities. • Major corporations. • Used for global weather forecasting, military defense, astronomy. • Billions to trillions of operations per second. • Millions of dollars.
Control Input Processing Storage Output The Computer System Concept • A computer system is an interrelated combination of components performing basic functions to provide end users with a powerful information processing tool. Computer System
Computer Processing Speeds • Early computers • Milliseconds (thousandths of a second) • Microseconds (millionths of a second) • Current computers • Nanoseconds (billionth of a second) • Picoseconds (trillionth of a second) • Program instruction processing speeds • Megahertz (millions of cycles per second) • Gigahertz (billions of cycles per second) • Commonly called “clock speed”
Peripherals Generic name for all input, output, and secondary storage devices Peripheral Depend on direct connections to the CPU of a computer system All online devices Separate from the CPU, but electronically connected to (and controlled by) it Online Devices Separate from, and not under the control of, the CPU Offline Devices
Input Technologies • Common input devices: Keyboard. • Pointing Devices: • Examples: • Electronic mouse and trackball. • Pointing stick • Touch pad. • Touch screen.
Pen-Based Computing Pen-Based: • Used in Tablet PCs and PDAs • They have a Pressure-sensitive layer, similar to touch screen, under liquid crystal display (LCD) screen. • Software digitizes handwriting, and hand drawing. • Examples: Graphics Tablet, Digitizer.
Speech Recognition Systems Speech Recognition: • Speech may be the future of data entry because it’s the easiest, most natural means of human communication. • Recognizing speech patterns: • Discrete speech recognition: requires pauses between each word. • Continuous speech recognition (CSR) recognizes continuous speech.
Speech Recognition Software • Speech recognition systems digitize, analyze, and classify your speech and its sound patterns: • Comparesyour speech patterns to a database of sound patterns • Passes recognized words to your software • Speech recognition SW requires voice recognition training • Speaker-independent voice recognition systems: • Allow computers to recognize words from a voice never heard before • Used in voice-messaging computers, computerized telephone call switching.
Optical Scanning Sheet-fed scanner Flatbed scanner • Devices read text or graphics and convert them into digital computer input. • Enables direct entry of data from source documents into a computer system. • Document management library system • Scans documents, then organizes and stores them for easy reference or retrieval. Optical scanner, copier, fax & printer
Compact desktop models are popular for low cost and ease of use • Larger, more expensive flatbed scanners are faster, offer high-resolution color scanning Software that reads characters and codes Used to read product labels, airline tickets, score tests, read bar codes Optical Scanning Scanners Optical Character Recognition (OCR)
Other Input Technologies • Magnetic stripe • Read magnetic stripe on credit cards • Smart cards • Microprocessor chip and memory . • Digital cameras • Digital Camcorder. • Magnetic Ink Character Recognition (MICR) • Identification numbers of bank and account printed in magnetic ink on bottom of check.
Output Technologies Voice Response Increasingly found along with video displays in business applications Cathode-ray tube (CRT) Video Displays Liquid crystal display (LCD) Plasma displays • Inkjet , laser, multifunction model Printed Output
Computer Storage Fundamentals • Data processed & stored in computer systems through presence or absence of signals , Either ON or OFF Uses two-state binary data representation On (1) or Off (0) Smallest element of data Bit Either 0 or 1 Group of eight bits, which operate as a single unit Byte Represents one character or number
Storage Capacity Measurement One thousand bytes Kilobyte (KB) Megabyte (MB) One million bytes One billion bytes Gigabyte (GB) Terabyte (TB) One trillion bytes One quadrillion bytes Petabyte (PB)
Direct (Random) and Sequential Access • Direct Access or Random Access • Directly store and retrieve data. • Each storage position has unique address and can be accessed in same length of time. • Semiconductor memory chips, magnetic disks. • Sequential Access • Data is stored and retrieved in a sequential process. • Must be accessed in sequence by searching through prior data. • Magnetic tape.
Semiconductor Memory • The primary storage (main memory) of your computer consists of microelectronic “semiconductor memory “chips. • It provides you with the working storage your computer needs to process your applications. • Advantages: small size, fast, shock and temperature resistance • Disadvantages: volatility; must have uninterrupted electric power or the contents of the memory will be lost. or permanently “burn in” the contents so they cannot be erased by a loss of power.
Types of Semiconductor Memory Read-Only Memory (ROM) Random Access Memory (RAM) Flash Drives “Jump Drive” 1. Permanent storage 2. Can be read, but not overwritten 3. Frequently used programs (parts of OS) burned into the chips during manufacturing 4. Called firmware 1. Most widely used primary storage medium 2. Volatile memory 3. Read/write memory • New type of permanent storage, can store data for unlimited periods without power. • Easily transported • Plugs into any USB port.
Hard Disk Drives & Floppy Disks (diskettes) Magnetic Disks • Used for secondary storage • Fast access and high capacity • Reasonable cost Types of Magnetic Disks: • Floppy disks • A single magnetic disk inside a plastic jacket • Hard disk drives • Magnetic disks, access arms, and read/write heads in sealed module.
Magnetic Disks • RAID (Redundant arrays of independent disks) • Disk arrays of interconnected hard disk drives. • They combine from 6 to more than 100 hard disk drives into a single unit. • Provide large capacities (1-2 TB or more). • Provide fault tolerant with multiple copies on several disks • Storage area networks (SANs) are high speed fiber channel local area networks that can interconnect many RAID units and thus share their capacity through network servers with many users.
Magnetic Disks • Magnetic Tape: • Include Tape reels, and cartridges (larger capacity). • Lower-cost storage solution • Usedfor: long term archival and backup storage Tape Cartridge Tape Reel
Uses of Optical Disks in Business Long-term storage ofhistorical image files Image Processing Storage of scanned documents Allows fast access toreference materials Publishing Medium Catalogs, directories ,manuals and so on Interactive Multimedia Applications in business Multimedia encyclopedias, Video games, educational videos, and so on
Resources .. • Read from Chapter 3 (Section 1,2)