Managing information systems 7th edition brow ch02

BASIC COMPONENTS OF COMPUTER SYSTEMS• All computers made up of the same set of six building blocks: input, output, memory, arithmetic/logic unit, control unit, and files • Control unit a

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MANAGEMENT INFORMATION SYSTEMS

CHAPTER 2

COMPUTER SYSTEMS

-HARDWARE

-SOFTWARE

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Chapter 2 Chapter 2 Chapter 3 Chapter 4

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BASIC COMPONENTS OF COMPUTER SYSTEMS

• All computers made up of the

same set of six building blocks:

input, output, memory,

arithmetic/logic unit, control

unit, and files

• Control unit and

arithmetic/logical unit together

known as the central processing

unit (CPU)

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• Device(s) needed to enter

data into the computer for it

to use in computations and

comparisons

Input:

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• Terminal

- Designed strictly for input and output

- Has keyboard and screen

- Does not have a processor

- Connected to a computer with a processor via telecommunications

- Examples: point-of-sale terminal, ATM

Input: What is the difference between a terminal

and a PC?

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- Keyboard: input entered by user through keystrokes

- Mouse, stylus, touchpad: alternative to keystrokes

- Disk drive or flash drive: data on disk read into memory

- Magnetic ink character recognition (MICR): used to process

bank checks

- Barcode labeling: scans barcodes on packages or products, and

reads into computer

- Optical character recognition (OCR): directly scans typed,

printed, or handwritten material

- Imaging: inputs digital form of documents and photos

Common Input Methods:

Keyboard Disk Drive

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• Device(s) needed to produce

results in a usable format

Output:

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- Video display unit: displays output on a screen

- Disk drive or flash drive: output written to disk for storage

- Printer: output to paper (various types of printers)

- Computer output microfilm (COM): microfilm generated

for archive copies in small space

- Voice response units: computer-generated verbal response

messages

Common Output Methods:

Video Display Disk Drive

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• Referred to as main memory or

primary memory

• All data flows to and from

memory

• Divide into cells

- Each has a unique address

- Can only store limited amount of

data

-Byte: stores one character of data

-Word: stores two or more

characters of data

Memory:

Memory

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Memory:

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• Each memory cell is a set of circuits

• Each circuit is on or off (represented by 1 or 0)

• Each circuit corresponds to a bit (binary digit)

• Most computers – 8 bits (circuits) represents a character (byte)

• 2 common bit coding schemes used today:

- ASCII

- EBCDIC

Memory:

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• Carries out:

- Mathematical operations

(addition, subtraction, multiplication, division)

- Logical operations

(number comparisons)

Arithmetic/Logical Unit:

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• Consists of VLSI circuits on a silicon chip

• Can perform up to billions of operations per second

• Numbers are taken from memory as input and results are

stored in memory as output

Arithmetic/Logical Unit:

ALU Circuits

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• File devices used to store vast

quantities of data

• Main memory is limited, volatile

and expensive

• Advantages:

- File devices or secondary memory are

used to store additional data that is

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• Sequential Access Files

- Records are stored in sequence according to file’s control key

- Usually stored on magnetic tape

• Direct Access Files

- Records can be accessed immediately, without regard to physical location

- Stored on Direct Access Storage Devices (DASD)

Types of Computer files:

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DIRECT ACCESS STORAGE DEVICES

• Types of DASD:

• Fixed (hard) drives

• Optical disk storage

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• Controls the other five

components of the computer

system

• Used to take advantage of speed

and capacity of other components

• List of operations, called a

program, tells the control unit

what to do

• These operations are read from

memory, interpreted, and carried

out one at a time (stored-

program concept)

Control unit:

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STORED-PROGRAM CONCEPT

• Computer Program

- A list of what is to be done for an application

- Each step or operation is called an instruction

• Machine Language

- Computer program written for specific computer model

- Program executed by control unit; consists of operation code and

addresses

• Measure of Computer Power

- Millions of instructions per second (MIPS)

- Millions of floating point operations per second (MFLOPS)

• Benchmarking is used to compare speed for running a set of jobs on

different machines

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TYPES OF COMPUTER SYSTEMS

Table 2.1

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• For personal computing

• Can generally be carried or moved by one person and only

have one keyboard and display unit

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Microcomputers:

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• Two major microcomputer platforms

- IBM-compatible PCs (personal computers)

- Apple microcomputers (does not use Windows OS)

• Have been put to a myriad of uses

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• In 1980s, included 2 types of computer systems

1 Workstations

- Microcomputers with more powerful chips than PCs

- Reduced instruction set computing (RISC) chip yielded greater performance because it was specialized

2 Minicomputers

- Less powerful and less expensive than mainframe systems

- Used for departmental computers & office automation

Midrange systems:

Midrange Systems

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• Servers for client/server applications, Web server, etc

- Usually run Linux or some variation of UNIX

Midrange systems - today:

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• Computer platforms for most major corporations and

government agencies

• Major strength is versatility in application processing

- Online and batch processing

- Integrated enterprise systems

- Engineering and scientific applications

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• “Number-crunchers” at 250K MFLOPS

• Handle problems generated by research scientists

• High-end supercomputers located in government, R&D labs,

major universities

• Cost: $1 - $100 million

• One of fastest supercomputers (IBM Blue Gene/P):

294,912 processors and can achieve speed of 1 petaflop

Supercomputers:

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SOFTWARE

Chapter 2 Chapter 2 Chapter 3 Chapter 4

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TWO CATEGORIES OF SOFTWARE

1 Applications software

2 Support software

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APPLICATIONS SOFTWARE

• Programs written to accomplish particular business tasks:

accounting, payroll, inventory, sales invoicing, etc

• Programs that users interact with

• Software for standard applications typically purchased from a

vendor

• Software for applications unique to the organization typically

developed internally or via a vendor contract

• Includes personal productivity software by knowledge workers

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APPLICATIONS SOFTWARE EXAMPLE

• Accounting Software Package:

- Commercial accounting package for smaller businesses

- Includes general ledger, accounts receivable, accounts payable, inventory, payroll, time and billing, job costing, fixed asset accounting, and analysis and reporting tools

- Price: $500 for single-user version

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APPLICATIONS SOFTWARE EXAMPLE

Personal Productivity Software

may be purchased as a software suite

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• Database management systems

- Used to create, manage and protect organizational data

- All employ a relational data model

• Database

- Is a shared collection of logically related data organized to meet organizational needs

- MS Office Example : Access

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• Presentation graphics

- Used to create slide shows for business presentations

- All allow embedding of clip art, photos, graphs, and other media

- MS Office Example: PowerPoint

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- MSOffice Example : Outlook

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• Used to access information (navigate) on the WWW from

computers that can access the Internet

- Hypertext-based approach (to link text and media objects to each other)

• Pull technology: browser requests a Web page before it is

sent to client

• Push technology: data sent to client without requesting it

(such as e-mail, spam, software patches)

• Examples:

Internet Explorer (Microsoft), Firefox (Mozilla), Safari (Apple)

WWW Browsers

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SUPPORT SOFTWARE

• Enables applications software to be carried out (run)

• Ensures that computer hardware and software are used efficiently

• Purchased from a hardware or software vendor

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• Usually purchased from manufacturer of computer hardware

that OS will be used on

• Complex program that controls operation of computer

hardware and coordinates other software

• Performance objective is to maximize work done (throughput)

• User communicates with operating system software for input,

output, storage, etc

• Easier to use with graphical user interface (GUI): click on

icons instead of enter text commands

Operating System (OS)

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Operating System

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• Job control language (JCL): instructions used to communicate with the operating

system

• Multiprogramming: employed on larger machines to overlap input and output

operations with processing time, keeping the CPU busy and speeding up execution

• Multitasking: similar to multiprogramming, but employed on microcomputers

• Multithreading: similar to multitasking, but multiple threads within the same

program are overlapped

• Multiprocessing: work that takes place when two or more CPUs are installed on

same computer system

Operating System Concepts

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• Virtual Memory:

- Optimizes management of main memory by switching in and out portions of programs from DASD

Permits multiprogramming to operate more efficiently

Operating System Concepts, cont.

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- Proprietary systems: operating systems written for a particular

computer hardware configuration

- Microcomputers: MS-DOS, Vista, Windows 7, Mac OS

- Large systems: IBM z/OS and z/VM

- Open systems: not tied to any particular computer system or

hardware manufacturer – will run on virtually any computer

• Examples: UNIX and Linux

- IT Platform: set of hardware, software, communications ; OS

name usually implies platform

Operating System Concepts, cont.

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- Software running on a server that manages network resources and controls the operation of a network

- Enhanced operating system that allows for:

- Sharing disk drives and printers

- Handling server side of client/server applications

- Major players include:

- UNIX and Linux

- Microsoft Windows Server

Server or Network Operating System (NOS)

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• Machine language (1GL)

• Each instruction must be expressed in unique form for a

particular computer

• Complete program consists of thousands of instructions

• Programming is a tedious, time-consuming process

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First and Second Generation Languages

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• Procedural languages (3GL)

- Express a step-by-step procedure devised by the programmer

- Typically machine independent

- Easier for programmers to learn

- Structured programs: divided into modules, where each has one entry and one exit point

- Must be compiled or interpreted (translated into machine language) ; one 3GL instruction typically translates into many machine language instructions

Third Generation Languages

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Compiling and running a 3 GL Program

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Developing programs with a 3GL

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• Most popular procedural languages & decade introduced

1950s - FORTRAN1960s - COBOL (COmmon Business Oriented Language)

BASIC1970s – C

Third Generation Languages

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COBOL program example

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• Nonprocedural languages (4GL)

• Easier to program, but less efficient for computers to run

• Uses more English-like statements for program instructions

• Today may be referred to as a language for business intelligence (BI) application development

• SAP Business Objects

• Oracle BI Enterprise Editing Plus

• Microsoft SQL 2008 Services (Analysis, Reporting)

Fourth Generation Languages

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• Employ tags to “mark up” documents

- Used to create Web pages

- Consists of special tags that tell the Web browser how to display various

elements on a Web page (e.g., bold-faced or italic text, image location, links to other Web pages)

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EXAMPLES

XML Example (tags in brackets)

Indiana vs Michigan

</Game>

XML Example

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• Neither 3GL nor 4GL … new paradigm

• Create objects once, store, then reuse

• Object examples:

- Text box, check box

• Most Common Languages:

- C++, Java, Visual Basic.NET, C#

Object-Oriented Programming (OOP) Languages

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Object-Oriented Programming – Java Example

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• HTML is the most common form of user interface

• Server-side programming languages include:

• PHP

• Java Servlets and Java Server Pages (JSP)

• Microsoft’s Active Server Pages (ASP, ASP.NET)

• Adobe’s ColdFusion

Languages for Developing Web Applications

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