Transcript 7. INFORMATION SYSTEMS SOFTWARE

Chapter 2
Hardware 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 comparisons
Control 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 Capacity
System 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 time
Clock 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 CPU
Digital circuits on chips
To 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)
Temporary
Volatile
Read-only memory (ROM)
Usually nonvolatile
Multiprocessing
Multiprocessing: simultaneous execution
of two or more instructions
Multicore 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 storage
Also called permanent storage
Nonvolatile
Greater capacity and greater economy than
memory
Access 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 stored
Sequential access storage devices (SASDs)
Direct access: data can be retrieved in any
order
Direct access storage devices (DASDs)
Secondary Storage Devices
 Magnetic tapes
 Optical disks
 Magnetic disks
 Digital video disk (DVD)
 RAID
 Flash memory
 Secondary storage used
primarily for backups
 Direct access secondary
storage, e.g., hard disk
 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
 Direct access optical disc,
e.g., CD-ROM
 Stores several gigabytes of
data
 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 output
Printers: laser, inkjet
Plotters: used for
general design work
Digital audio player
Stores, 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’ problemsolving capabilities
Different types of systems software
include:
Operating systems
Utility 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 user
Single computer with
multiple users
Multiple computers
Special-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
Operating Systems
Processing tasks
Multitasking: more than one program running at
the same time
Time-sharing: more than one person using a
computer system at the same time
Scalability: ability to handle an increasing
number of concurrent users smoothly
Networking capability: aids users in
connecting to a computer network
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
software
Enables 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 attention
Software bugs
Copyrights and licenses
Software upgrades
Global software support