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AN INTRODUCTION TO

INFORMATION SYSTEMS SOFTWAREIS 340

BY

CHANDRA S. AMARAVADI

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IN THIS PRESENTATION

Intro & types of SW Overview of systems software Operating systems

OS functions Applications Software Programming languages Applications of programming languages

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Detailed instructions to the computer to control information processing operations.

Software/SW Program:

COMPUTER

INPUTS OUTPUTS

INSTRUCTIONS

SW

Sw concerned with the system(Systems sw)

Sw for a specific purpose/ (Applications SW or simply“application”)

Operating Systems

Compilers

Utility

Packaged or “business” or COTs

Customized

Open source

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SYSTEMS SOFTWARE

OPERATING SYSTEM

COMPILERS

UTILITY PROGRAM

OPERATING SYSTEM: Software that manages and controls system operations.

COMPILERS: Convert a program (the “source program”) to machine code (“object code”).

UTILITY: Perform support functions inside the computere.g. screen savers, file management, network management, data conversion etc.

HARDWARE

SYSTEM SOFTWARE

APPLICATION SOFTWAREAPPLICATION SOFTWARE

EXAMPLES OF O/S

PC Environment Windows, Vista Mac OS

Workstation/server Unix, Linux

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Runs the hardware CPU, memory etc.

Interacts/monitors users keyboard commands passwords etc.

COMMON TASKS PERFORMED BY OS

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APPLICATIONS SOFTWARE

CUSTOMIZED APPLICATIONSInventoryAccounting Invoicing…….BUSINESS SOFTWAREWord processingSpreadsheetEmail……..

HARDWARE

SYSTEM SOFTWARE

APPLICATION SOFTWAREAPPLICATION SOFTWARE

Software for a specific purpose

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CUSTOMIZED SOFTWARESoftware tailored to the needs of a business

“application” generally refers to “customized” example resume processing, benefits system etc.

developed in 3rd GLs or OO languages interface may be less finished than business more expensive

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Example MS Word, Powerpoint etc. integrated under Windows

Common “look & feel” Point & Click -- GUI C&P functionality for DDE Dynamic, context dependent help

Note: DDE stands for Dynamic Data Exchange, C&P for cut and paste

Standardized software for a specific purpose

OPEN SOURCE SOFTWARE

publicly available or authored by the “public” aka “public domain” or “shareware” sometimes subscription/nominal fees e.g. Zimbra, Winscp

downside of open source?

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All SW is written in a programming language. Programming languages have evolved based on factors

such as useability, features, and application. Initially programming languages attempted to control

machine components (e.g. memory) As O/S evolved there was less of a need for programmers

to control machine components and more of a need to fulfill user requirements.(e.g reporting)

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1st e.g. Machine2nd e.g. Assembly

3rd e.g. COBOL, C

4th e.g. SQL, macros, Java Script5th e.g. Prolog, Java, C++

LLL

HLL

VHLL

Note: LLL = Low Level Languages; HLL = High Level LanguagesVHLL = Very High Level Languages

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M/C and Assembly languages low level hardware dependent high execution speed

THE FIRST TWO GENERATIONS

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N   ds   1   ; first 8-bit number M   ds   1   ; second 8-bit number P   ds   1   ; third 8-bit number

sub8s  ldaa   N   ; first number       suba   M   ; subtract second number ; V bit set if signed overflow       bvc  SetP ; skip if no overflow       bpl   floor ; is positive, should be -128 ceil   ldaa  #127 ; set at maximum (ceiling)       bra   SetPfloor  ldaa  #-128; set to minumum (floor)SetP   staa  P rts

ASSEMBLY CODE TO SUBTRACT TWO NUMBERS (FYI)

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The distinction between high level and lowlevel languages is based on the ratio ofthe # of lines of program code to the # ofactions carried out by the system

# of program lines : system actions

For L.L.L 1:1For H.L.L 1:10For VHLL 1:50

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CHARACTERISTICS OF 3rd GLs

languages like COBOL & C aka “traditional languages”; HLL 60% of installed apps. formal - characterized by program

structure (not present in 1st, 2nd GLs)

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CONCEPTUALIZING A PROGRAM

PROGRAM

INPUTS OUTPUTS

Module1 Module2

Module3 Module4

Data/variables

(A 3rd GL Program)

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FD BookMasterFile.01 BMF-Record. 02 BMF-BookNum PIC X(5). 02 BMF-BookTitle PIC X(25). 02 BMF-AuthorName PIC X(25).FD BookSalesFile.01 BSF-Record. 88 EndOfBSF VALUE HIGH-VALUES. 02 BSF-BookNum PIC X(5). 02 BSF-Copies PIC 99. 02 BSF-SaleStatus PIC X. 88 NormalSale VALUE "N".

EXAMPLE OF VARIABLES

01 Book-Rank-TABLE. 02 BookDetails OCCURS 11 TIMES. 03 BookNum PIC 9(5). 03 BookTitle PIC X(25). 03 AuthorName PIC X(25). 03 BookSales PIC 9(4) VALUE ZEROS.01 Rank PIC 99.01 PrevBookNum PIC X(5).01 BookSalesTotal PIC 9(4).

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Check_BookRank. IF BookSalesTotal >= BookSales(Rank) MOVE BookDetails(Rank) TO BookDetails(Rank + 1) MOVE BMF-BookNum TO BookNum(Rank) MOVE BMF-BookTitle TO BookTitle(Rank) MOVE BMF-AuthorName TO AuthorName(Rank) MOVE BookSalesTotal TO BookSales(Rank) END-IF.

EXAMPLE OF A MODULE (COBOL) -- FYI

PERFORM Check_BookRank VARYING Rank FROM 10 BY -1 UNTIL Rank < 1.

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THIRD GENERATION LANGUAGES (3rd GL)

program is modular; has many parts explicit declaration of variables; data “Typing”

Acct_bal -- Numeric

Name – AlphaNumeric use delimiters procedural

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THE FOURTH GENERATION

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Associated with various applns. software Scripting/”macro” language Examples include SQL, Macro, Java script etc. Idea is to specify only goals, not how

Provide a list of students and their current grade standing.Across Years down Sales, COGs, margin.

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EXAMPLES OF 4th GLs

<SCRIPT LANGUAGE="javascript">

document.write("<FONT COLOR='RED'>This Is Red Text</FONT>")

</SCRIPT>

Select Product.Name, Product.PriceFrom ProductWhere Product.price > $4000

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THE FIFTH GENERATION – AI LANGUAGES

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FIFTH GENERATION LANGUAGES (5TH GL)

involve symbolic reasoning, pattern matching as opposed to?

uses “facts”, “predicates” and clauses purpose of facts & predicates?

Sibling(X,Y) :- Parent_of (X,Z), Parent_of(Y,Z).

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FIFTH GENERATION LANGUAGES (5TH GL) -- FYI..

PREDICATES bank_balance(symbol, symbol) credit_status(symbol, symbol)

FACTS bank_balance(Mary, substantial) credit_status(Mary, excellent) bank_balance(Jeff, good) bank_balance(Mark, substantial) credit_status(Mark, good)

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FIFTH GENERATION LANGUAGES (5TH GL).. FYI

GOAL approve_loan(Mark)? approve_loan(Mary)? approve_loan(Jeff)?

CLAUSES approve_loan(X) :- bank_balance(X, substantial),

credit_status(X, good). approve_loan(X) :- bank_balance (X, reasonable), credit_status (X, excellent).

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THE FIFTH GENERATION – OO LANGUAGES

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Appln. a collection of objects, on which actions are taken

Classes are packaged to include data & methods Methods are actions involving data associated w

class Objects are grouped into classes

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CONCEPTUALIZING AN OO PROGRAM

PROGRAM

INPUTS OUTPUTS

Class1.methodData

Data

Data

Data

Class2.method

Class3.methodClass4.method

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CLASSES, OBJECTS..

Employee : John Smith

Department: FinanceSalary: $60,000 Manager: Steve

Update Salary (new_Salary)Change Department(new Department)Change Manager(new Manager)

PROPERTIES, METHODS

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OBJECT ORIENTED CONCEPTS..

WINDOW

Win1 …Win2 Win 4

Which of these are classes and which are objects?What might be some properties of the class?What might be methods associated with the class?

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OBJECT ORIENTED PROGRAMMING

Win1 = New WindowWin1.height = 10Win1.breadth = 20Win1.color = red

Win1.open.Win1.resize(15,5).Win1.close.

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uses “byte-code” or applets. applet: tiny program to execute small function applets sent over network. interpreted by local interpreter. run on any computer & operating system.

Machine independent object oriented language introduced by Sun Microsystems (subset of C++)

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L.L.L are efficient from the systems point of view. All languages need to be converted to m/c. language in

order to run on the Hardware. Parts of O/S in Assembly. H.L.L and V.H.L.L are convenient from the user’s point of

view.

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1st GLs inside m/c 2nd GLs for parts of system’s sw and some

applications sw. 3rd GL’s for conventional applns. 4th GLs associated with applications sw. 5th GL’s used in AI.

OO for conventional applns and Java for web applns.

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FOR DISCUSSION

What does systems software do? T/F: O/S is an example of systems software? What are other examples of systems software? What is the purpose of a compiler? What are examples of 5th Generation languages? What is the fundamental difference between 3rd & OO? What is Java? Why is it portable?

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