Software Concept

8/6/2019 Software Concept

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Introduction to Computers


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History of Computers - 19th

Century

first stored program -

metal cards

first computermanufacturing

still in use today!


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3 MIT School of Telecom Management

Charles Babbage - 1792-1871 Difference Engine c.1822

huge calculator, never

finished Analytical Engine 1833

could store numbers

calculating mill used

punched metal cards forinstructions

powered by steam!

accurate to six decimal places


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Computer SizeENIAC then

ENIAC today

With computers (small) size does matter!


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Discussion Question What was the biggest advance that led

to modern computers?

Electricity

Transistor

Microchip

Data storage


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Generations of Electronic

ComputersFirst

Generation

Second

Gen.

Third

Gen.

Fourth Gen.

Technology Vacuum

Tubes

Transistors Integrated

Circuits(multiple

transistors)

Microchips

(millions oftransistors)

Size Filled Whole

Buildings

Filled half a

room

Smaller Tiny - Palm

Pilot is as

powerful as

old building

sized

computer


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Algorithms What is an algorithm?

A step-by-step problem-solving procedure,

especially an established, recursivecomputational procedure for solving aproblem in a finite number of steps

Weve seen lots of algorithms before


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Example algorithm: mapdirections


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Computer Organization

Input Devices

CentralProcessing Unit

Memory

Output Devices


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A bit of humor: Computer

Organization


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Computing units of measure

A bit is either a 1 or a 0

On or off, true or false, etc.

A byte is 8 bits: 01001010

As there are 8 bits per byte, each byte can hold

2

8

=256 values 01001010 = 74

All computing measurements are in terms of

bytes


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Computing units of measure An unformatted text document (such as a Java program)

3 pages per kilobyte (1,000 bytes)

A formatted document (such as a Word file)

About 5k per page with formatting

A digital camera picture

About 1 Mb each (1,000,000 bytes)

An MP3 music file

5 Mb for a 5 minute song

A music file on a CD 50 Mb for a 5 minute song

10 times the size of an MP3!

A movie clip

About 10 Mb per minute of (TV-sized) video


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Software Concepts

MIT School of Telecom Management


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Software Concepts Aprogram is a set of instructions that tells

the computer what to do.

Software can be a single program or a groupof programs needed to perform severalfunctions.

Simple programs may have a few hundredinstructions (lines of code) though most havemany more (several million).



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Application Software



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Individual Application

Software Word processing

Spreadsheet

Graphics

Database

Browser



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Workgroup Application

Software Groupware

E-Mail software

Information sharing software

Electronic conferencing software



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Other Application Software Organizational application software

Generally organization specific

Interorganizational application software

Electronic Data Interchange (EDI)

Generally common to the participating

organizations



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System Software



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Operating System ConceptsAn operating system is a group of

programs that manages the operation

of the computer. Three functions of an operating system

Process management

Resource management

Data management



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Operating System Concepts

(contd.) Organization of an operating system

Most operating system programs are

stored in secondary storage. One operating system program is stored in

a section of primary storage. It goes byvarious names kernel but generically

called the supervisor. The supervisor controls all activity in

primary storage.



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Using an Operating System Starting the computer is called booting

which transfers the supervisor from

secondary storage to primary storage. Connecting to a network or other multi-

user environment is called logging in.

Detaching from a network is calledlogging out.



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Elements of an Operating

System User interface is the visual link between

the user and the software.

Small pictures on the screen are icons. Graphical User Interface (GUI) uses

Buttons

Icons Menus

Dialog boxes



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Capabilities of Operating

Systems Multitasking is appearing to execute

more than one program at a time,

though the CPU can executeinstructions from only one program at atime.



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Systems (contd.) Multi-user or Multiple-user programs

permit more than one person to use the

program, and data, at a time. One technique that is used with

multiple-user operating systems is time

sharing. With this technique, the usersare each allocated a small amount oftime by the operating system.



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Systems (contd.) Two types of operating systems

Batch operating systems where the first

program is executed and all dataprocessed before moving to the secondprogram.

Interactive operating systems allow user

interaction as the program executes. Mostpersonal computer operating systemspermit user interaction.



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Systems (contd.)Virtual memory is supplemental primary

storage (RAM) or real memory where

the programs are too big for primarystorage. It is created on a secondarystorage device, usually the hard drive,

and is generally temporary in nature.



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Systems (contd.)Virtual memory operating systems

execute large programs by dividing the

program into parts and transferring thenecessary parts of the program fromsecondary storage to primary storage as

needed. The transfer process does not require

any action by the user.



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Personal Computer Common

Operating Systems Microsoft Windows

Microsoft DOS (and others)

IBM OS/2

Apple Mac OS

UNIX Linux



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Multi-User Computer Common

Operating Systems IBM OS/390

Hewlett Packard MPE

(MultiProgramming Executive)

UNIX

Network Operating Systems

Novell Netware

Windows 2000 Server



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Other System Software Utility programs

Sort utility rearranges data in a specified

order Merge utility merges two files into one

Print utility prints the contents of a file

Copy utility copies data from one deviceto another



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Software Development



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Programming Language

Concepts What is a programming language?

Why are there so many programming

languages?

How do you select a programminglanguage?

What are the types of programminglanguages?



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What is a Programming

Language English is a natural language. It has

words, symbols and grammatical rules.

A programming language also haswords, symbols and rules of grammar.

The grammatical rules are called syntax.

Each programming language has adifferent set of syntax rules.



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Why Are There So Many

Programming Languages Programming languages have evolved

over time as better ways have been

developed to design them. Different programming languages are

designed for different types ofprograms.

First programs were developed in the1950s.



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How Do You Select a

Programming Language Is it designed for the type of program that

needs to be written?

Is it available on the computer being used?Are trained programmers available?

Is it easy to write programs in the

language? Is the language efficient when the program

is executed?



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What Are the Types of

Programming Languages First Generation Languages

Second Generation Languages

Third Generation Languages

Fourth Generation Languages

Fifth Generation Languages



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First Generation Languages Machine language

Operation code such as addition or

subtraction. Operands that identify the data to be

processed.

Machine language is machine dependent as it

is the only language the computer canunderstand.

Very efficient code but very difficult to write.



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Second Generation LanguagesAssembly languages

Symbolic operation codes replaced binary

operation codes.Assembly language programs needed to beassembled for execution by the computer.Each assembly language instruction is

translated into one machine languageinstruction.

Very efficient code and easier to write.



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Third Generation Languages Closer to English but included simple

mathematical notation.

Programs written in source code which mustbe translated into machine languageprograms called object code.

The translation of source code to object codeis accomplished by a machine languagesystem program called a compiler.



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Third Generation Languages

(contd.)Alternative to compilation is interpretation

which is accomplished by a system

program called an interpreter. Common third generation languages

FORTRAN

COBOL

C and C++

Visual Basic



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Fourth Generation Languages A high level language (4GL) that requires

fewer instructions to accomplish than a third

generation language. Used with databases

Query languages

Report generators

Forms designers

Application generators



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Fifth Generation Languages Though no clear definition at present,

natural language programs generally

can be interpreted and executed by thecomputer with no other action by theuser than stating their question.

Limited capabilities at present.



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Programming Languages Two broad groups

Traditional programming languages

Sequences of instructions First, second and some third generation

languages

Object-oriented languages

Objects are created rather than sequences ofinstructions

Some third generation, and fourth and fifthgeneration languages



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Traditional Programming

Languages FORTRAN

FORmula TRANslation.

Developed at IBM in the mid-1950s.

Designed for scientific and mathematicalapplications by scientists and engineers.



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Languages (contd.) COBOL

COmmon Business Oriented Language.

Developed in 1959.

Designed to be common to many differentcomputers.

Typically used for business applications.



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Languages (contd.) BASIC

Beginners All-purpose Symbolic Instruction

Code. Developed at Dartmouth College in mid

1960s.

Developed as a simple language forstudents to write programs with which theycould interact through terminals.



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Languages (contd.) C

Developed by Bell Laboratories in the early

1970s. Provides control and efficiency of assembly

language while having third generationlanguage features.

Often used for system programs.

UNIX is written in C.



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Object-Oriented Programming

Languages Smalltalk

First object-oriented language.

Developed by Xerox in mid-1970s.

Still in use on some computers.



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Object-Oriented Programming

Languages (contd.) C++

It is C language with additional features.

Widely used for developing system andapplication software.

Graphical user interfaces can be developed

easily with visual programming tools.



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Special Programming

Languages HTML

HyperText Markup Language.

Used on the Internet and the World WideWeb (WWW).

Web page developer puts brief codes

called tags in the page to indicate how thepage should be formatted.



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Special Programming

Languages (contd.) XML

Extensible Markup Language.

A language for defining other languages.



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Special Programming

Languages (contd.) JAVA

An object-oriented language similar to C++

that allows a web page developer to createprograms for applications, called appletsthat can be used through a browser.

Objective of JAVA developers is that it bemachine, platform and operating systemindependent.



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Translation

Translator

Accepts a program written in a source language andtranslates it to a program in a target language

Compiler

Standard name for a translator whose sourcelanguage is a high-level language

Interpreter A translator that both translates and executes a

source program


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Software Concepts

Key Terms



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Key Terms

Assembler

Assembly Language

BASIC

Booting

Browser

Button

C C++

COBOL

Command

Compiler

Database Software

Dialog Box

Electronic ConferencingSoftware

Electronic MessagingSoftware

FORTRAN



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Key Terms (contd.)

Fourth-GenerationLanguage (4GL)

Graphical User Interface

(GUI)

Graphics Software

Groupware

HTML

Icon

Information SharingSoftware

Interpreter

Java

Menu

Multitasking

Network OperatingSystem (NOS)

Object



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Key Terms (contd.)

Object-OrientedProgramming

Operating Environment

Page

Programmer

Programming

Programming Language Prompt

Spreadsheet Software

Time-Sharing

User Interface

Utility Program

Virtual Memory

Window

Word Processing

Software XML

Documents

Software Concept