Chapter 2Hardware and Software

Why Learn About Hardware and Software?

Hardware can improve productivity, increase revenue,

reduce costs, and provide better service

Managers are expected to know about hardware

To help define business needs

To ask questions and evaluate options when buying equipment

Software is indispensable for any computer system

Systems software needed for input, calculations, and

output

Application software aids in productivity

Hardware Components

Central processing unit (CPU)Arithmetic/logic unit (ALU): performs calculations and

makes logical comparisonsControl unit: accesses, decodes and coordinates data

in CPU and other devices

Primary memory: holds program instructions and data for processing

Secondary storage: more permanent storage Input and output devices Communications devices

Hardware Components

Figure 2.1: Hardware Components

Processing and Memory Devices: Power, Speed, and

CapacitySystem unit

Houses the components responsible for processing (the CPU and memory)

All other computer system devices are linked either directly or indirectly into the system unit housing

Processing Characteristics and Functions

Clock speed: series of electronic pulses produced at a predetermined rate that affects machine cycle timeClock speed is often measured in

megahertz (MHz), or millions of cycles per second

Clock speed for personal computers is in the multiple gigahertz (GHz), or billions of cycles per second, range

Processing Characteristics and Functions

Physical characteristics of the CPUDigital circuits on chipsTo turn a digital circuit on or off, electrical

current flows through silicon

Memory Characteristics and Functions: Storage Capacity

Table 2.1: Units for Measuring Computer Storage

Memory Characteristics and Functions: Types of Memory

Random access memory (RAM)TemporaryVolatile

Read-only memory (ROM)Usually nonvolatile

Multiprocessing

Multiprocessing: simultaneous execution of two or more instructionsMulticore microprocessor: shares

workload among two or more independent processors in a single computer

Parallel processing: links several processors to operate at the same time, or in parallel

Grid computing: collection of computers working to solve a common problem

Secondary Storage and Input and Output Devices

Secondary storageAlso called permanent storageNonvolatileGreater capacity and greater economy than

memoryAccess methods, storage capacities, and

portability required are determined by the information system’s objectives

Access Methods

Sequential access: data must be accessed in the order in which it is storedSequential access storage devices (SASDs)

Direct access: data can be retrieved in any orderDirect access storage devices (DASDs)

Secondary Storage Devices Magnetic tapes

Secondary storage used primarily for backups

Magnetic disks Direct access secondary

storage, e.g., hard disk

RAID Stores extra bits so that

data can be reconstructed if system fails

SAN Provides high-speed

connections between data storage devices and computers over a network

Optical disks Direct access optical disc,

e.g., CD-ROM

Digital video disk (DVD) Stores several gigabytes of

data

Flash memory Nonvolatile silicon

computer chip

Input Devices Personal computer input

devices Keyboard, mouse

Speech-recognition technology Input devices that recognize

human speech

Digital cameras Input device used with PC to

record/store images in digital form

Terminals Input and display devices

that perform data entry and input at the same time

Touch-sensitive screens Allow display screens to act as

input devices as well as output devices

Bar-code scanners Employs a laser scanner to read

a bar-coded label Magnetic ink character

recognition (MICR) devices Code data on banking forms,

such as checks Pen input devices

Activate a command, enter handwritten notes, and draw objects

Radio Frequency Identification (RFID) Employs a microchip with an

antenna to broadcast its unique identifier and location to a receiver

Output Devices

Display monitors (CRTs) Output quality measured by

number of pixels and dot pitch

Liquid crystal displays (LCDs) Easier on eyes, use less

electricity, take up less space than CRTs

Organic light-emitting diodes (OLEDs) Directly emits light rather

than using backlight Sharper colors and thinner

displays

Printers and plotters: hard copy outputPrinters: laser, inkjet Plotters: used for

general design work

Digital audio playerStores, organizes, and

plays digital music files

Computer System Types

Table 2.3: Types of Computer Systems

Overview of Software

Computer programs: sequences of instructions for the computer

Documentation: describes program functions

Systems software: coordinates the activities of hardware and programs

Application software: helps users solve particular problems

Supporting Individual, Group, and Organizational Goals

Table 2.4: Classifying Software by Type and Sphere of Influence

Systems Software

Controlling operations of computer hardware is one of the most critical functions of systems software

Also supports application programs’ problem-solving capabilities

Different types of systems software include:Operating systemsUtility programs

Operating Systems

Operating system (OS): programs that control the hardware and interface with applications

Common hardware functions Get input (e.g., keyboard) Retrieve data from disks

and store data on disks Display information on a

monitor or printer

Combinations of OSs, computers, and users:Single computer with a

single userSingle computer with

multiple usersMultiple computersSpecial-purpose

computers

Operating Systems

Figure 2.8: The Role of Systems Software

Operating Systems Activities performed by the operating

system Perform common computer hardware

functions Provide a user interface and

input/output management Provide a degree of hardware

independence Manage system memory Manage processing tasks Provide networking capability Control access to system resources Manage files

Hardware independence Application program interface

(API): allows applications to make use of the operating system

Memory management Converts a user’s request for data or

instructions to the physical location where the data or instructions are stored

Common hardware functions Get input from keyboard or some other

input device Retrieve data from disks Store data on disks Display information on a monitor or

printer

User interface Allows individuals to access and

command the computer system Command-based user interface:

uses text commands Graphical user interface (GUI): uses

icons and menus to send commands to the computer system

Operating Systems

Figure 2.9: Application Program Interface Links Application Software to the Operating System

Processing tasksMultitasking: more than one program

running at the same timeTime-sharing: more than one person using

a computer system at the same timeScalability: ability to handle an increasing

number of concurrent users smoothlyNetworking capability: aids users in

connecting to a computer network

Operating Systems

Operating Systems

Access to system resources Protection against

unauthorized access Logins and passwords

File management Ensures that files in

secondary storage are:

Available when needed

Protected from access by unauthorized users

Application Software Give users the ability to solve problems and

perform specific tasks Interact with systems software; systems

software then directs the hardware to perform tasks

Types and Functions of Application Software

Personal Application Software

Serves the needs of an individual user

Includes personal productivity softwareEnables users to

improve their personal effectiveness

Personal Application Software

Table 2.7: Examples of Personal Productivity Software (continued)

Workgroup Application Software

Workgroup application software: support teamwork, whether people are in the same location or dispersed around the world

Groupware: software that helps groups of people work together more efficiently and effectively

Enterprise Application Software

Software that benefits an entire organization

Enterprise resource planning (ERP) software: programs that manage a company’s vital business operations for an entire multisite, global organization

Programming Languages

Table 2.11: The Evolution of Programming Languages

Software Issues and Trends

Software issues and trends receiving increasing attentionSoftware bugsCopyrights and licensesSoftware upgradesGlobal software support