Software

1
Software

• If builders built buildings the way programmers
  wrote programs, then the first woodpecker that
  came along would destroy civilization.
• Weinberg's Second Law

2
Two Categories of Software

• Systems s/w - to make the hardware easier and
  more efficient to use
• Application s/w - developed to solve a particular
  user need
• Difference in orientation
• Application - users
• Systems - computer

3
Components of Systems Software

• Operating System
• Utilities
• Communications
• Database management systems
• Language translators

4
Operating System

• Puts resources of the computer at the disposal of
  programs in an efficient, orderly manner
• Manage flow of information between devices
• Example - pressing a key on a PC

application
system
computer
5
Microsoft vs. Justice Dept.

• Difference between systems and application
  software
• Video news segment from NewsHour
• Where does a browser belong?
• Settlement reached, but not everyone happy (state
  suits)
• Europe weighing in

6
Utilities

• Perform support functions
• Sort files
• Re-organize DASD
• Security
• Monitor performance
• May be provided by third party

7
Communications

• Handles communcations with remote facilities
• Monitors the network for traffic patterns
• Diagnosis of problems
• On microcomputer, can emulate a terminal, handle
  connection to Internet

8
Database Management Systems

• Enables orderly access to data
• Will discuss in more detail later

9
Language Translators

• What is a computer language?
• An agreement/understanding of how we will express
  what we want the computer to do.
• But computer does not understand things as we do.
• A statement in the BASIC language
• 10 IF A gt 100 THEN BAA

10
Language Translators (cont.)

• To translate a program (source code) into
  something the computer can understand
• Compilation Interpretation

Source code
Instructions
Executable
Computer
11
Some Languages

• COBOL - Common Business Oriented Language
• For business applications
• Lots of I/O handling facilities (defining files,
  reading and writing data)
• Wordy (for maintainability)
• Good iteration constructs
• Batch-oriented
• Weak on heavy-duty math
• Majority of legacy code

12
Cobol (cont.)
3500-PROCESS-PAYROLL-CALCULATION.

CALLED FROM 1200

IF HOURS-WORKED
GREATER THAN 40 PERFORM 3512-CALCULATE-OVERTIME
THRU 3512-EXIT. MULTIPLY EMPLOYEE-HOURS BY
EMPLOYEE-RATE GIVING GROSS-PAY. ADD OVERTIME-PAY
TO GROSS PAY. 3500-EXIT EXIT.
13
Fortran (Formula Translation)

• For scientific and technical applications
• Fewer I/O capabilities - relatively small data
  sets
• Emphasis on processing complex equations

10 BLN(A)SIN(C)(QX)ARCTAN(T)
14
BASIC - Beginners All-purpose Symbolic
Instruction Code

• Easy to learn and use
• Standard Equipment with MS-DOS
• Similar to FORTRAN
• Not very standardized
• Visual Basic
• Turbo Basic
• Limited power

15
BASIC (cont.)
10 A1 15 BSQRT(A) 20 PRINT A, B 25 AA1 30
IF A gt 100 THEN GOTO 40 35 GOTO 15 40 STOP
16
C and C

• Language of choice for micro software development
• Very cryptic
• Forces structure onto the programmer (no GOTO
  statement)
• Powerful

17
C and C (cont.)
include ltstdio.hgt define KILOS_PER_POUND
.45359 main() int pounds
printf(" US lbs UK st. lbs INT
Kg\n") for(pounds10 pounds lt 250
pounds10) int stones pounds /
14 int uklbs pounds 14
float kilos pounds
KILOS_PER_POUND printf(" d
d d f\n",
pounds, stones, uklbs, kilos)

18
Java

• Developed by Sun Microsystems
• Used in web pages
• Promises
• Ultimate in portability
• Enliven WWW pages
• Problems - security, performance, Microsoft

19
Java (cont.)
public class Quizzer extends Applet
JetPanel xframe public void init()
Db.localAPI(false) xframe new
JetPanel() xframe.x.set(0)
xframe.y.set(0) xframe.width.set(600)
xframe.height.set(400)
((Panel)xframe.getAwtComponent()).setLayout( null
) QuizzerControlPanel panel new
QuizzerControlPanel( 10, 300, 650, 200 )
panel.xframe xframe xframe.add( panel
) JetLabel qnumlabel new
JetLabel()
20
Examples of Systems Software

• MVS (IBM mainframes)
• Unix and variants (Linux, Solaris)
• MS-DOS (Original PC)
• Macintosh OS X

21
Windows

• Benefits
• Multitasking
• Standard GUI for software
• Device independence

22
Applications Software

• Two major categories (my divisions)
• Office automation productivity tools
• Word processing
• Spreadsheets
• Presentation graphics
• Project management
• Desktop publishing
• Others?
• Information Systems (remainder of course)