COMPUTER HARDWARE

CHAPTER 3

Lecture-4 / T. Nouf Almujally

1

Outline

Section 1:• History (Homework)• Types of Computer Systems.• The computer System Concept.

Section 2:• Peripherals:

• Input Technologies.• Output Technologies.• Storage Technologies.

Types of Computer Systems

Microcomputer Systems

Computing power now exceeds that of the mainframes of previous generations

Called a personal computer or PC

Relatively inexpensive

Desktop, Hand-held, notebook, laptop, tablet, portable, and floor-standing

Home , personal , professional , workstation or multiuser systems.

Recommended PC Features

Microcomputer Systems

Workstations

-Supports heavy mathematical computing and graphics display demands

Ex:- CAD in engineering,- Portfolio analysis.

Network Servers

-More powerful than workstations

-Coordinates telecommunications and resource sharing

-Supports LAN and Internet.

Terminals

• Terminal: is any input/output device connected by a network to a computer.

• Types:1. Dumb terminals: keyboard and video monitor with

limited processing capabilities.2. 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

3. 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.

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

Input

Processing

Output

Storage

Control

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)• 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

Separate from, and not under the control of, the CPUOffline Devices

Separate from the CPU, but electronically connected to (and

controlled by) itOnline Devices

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

Peripherals Advice for a business PC

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:• Compares your 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

• 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.

Sheet-fed scanner Flatbed scanner Optical scanner, copier, fax &

printer

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

Software that reads characters and codes

Used to read product labels, airline tickets, score

tests, read bar codes

• 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.

Other Input Technologies

Output Technologies

Voice Response Increasingly found along with video displays in business

applications

Video Displays Cathode-ray tube (CRT)

Printed Output Inkjet , laser, multifunction model

Liquid crystal display (LCD)

Plasma displays

Computer Storage Fundamentals

On (1) or Off (0)

Data processed & stored in computer systems through

presence or absence of signals , Either ON or OFFUses two-state

binary data representation

Uses two-state binary data

representation

Smallest element of data

Either 0 or 1BitBit

Group of eight bits, which operate as a single unit

Represents one character or numberByteByte

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 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

Random Access Memory (RAM)

Read-Only Memory (ROM)

1. Most widely used primary storage medium

2. Volatile memory

3. Read/write memory

1. Permanent storage2. Can be read, but not

overwritten3. Frequently used

programs (parts of OS) burned into the chips during manufacturing

4. Called firmware

Flash Drives“ Jump Drive”

1. New type of permanent storage, can store data for unlimited periods without power.

2. Easily transported3. Plugs into any USB

port.

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.

Hard Disk Drives & Floppy Disks (diskettes)

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• Used for: long term archival and backup

storage

Tape CartridgeTape Reel

Optical Disks

Uses of Optical Disks in Business

Image ProcessingLong-term storage ofhistorical image files

Storage of scanned documents

Publishing Medium

Allows fast access toreference materials

Catalogs, directories ,manuals and so on

Interactive Multimedia

Applications in business

Multimedia encyclopedias, Video games, educational videos, and so

on

Storage Trade-offs

Questions ..

Read from Chapter 3 (Section 1,2)

Resources ..