1. Calculators are used to increase speed and accuracy of numerical computations
The abacus has roots dating back over 5,000 years
Mechanical calculators have been relatively commonplace since late 19th century
What is a computer?
A mechanical or electronic device
Stores, retrieves, manipulates large amounts of data (information) at high speed, with great accuracy
Does not need human intervention
Carries out instructions from a program

2. Early Computers 1945 – 1950’s: First generation computers
used vacuum tubes to do internal switching needed for computations
1955: about 300 computers in the world built mostly by IBM and Remington Rand, based on vacuum tubes.
Late 1950s: invention of the transistor was one of most important inventions of 20th Century
computers based on the transistor are the first solid-state computers.
Early 1960’s: DEC created the minicomputer (Servers) – about the size of a file cabinet.
Used small packages of transistors called integrated circuits
Mainframes, such as the IBM 360 are prominent in large companies and Universities.

3. The Personal Computer
1970s: The personal computer becomes available with invention of the microchip
1974: The microchip, along with the invention of the microprocessor led to creation of first personal computer
Bill Gates and Paul Allen founded Microsoft Corporation
Stephen Wozniak and Steven Jobs founded Apple Computer, Inc.

4. Computers Today Currently:
PCs: 95% use Microsoft Windows operating system with a huge array of available software
Minicomputers (servers) are still popular with small business and universities.
Mainframes are in use at large corporations.
Supercomputers are very powerful and specialized
Used for massive computing problems by big corporations and government departments.

5. Components and Operations
Hardware: equipment, or devices
Software: programs that contain instructions which tell the computer what to do – created by programmers
Hardware and software: the two major
components of any computer system
Major operations in a computer:
Input
Processing
Output

6. Input devices: allow data to enter the computer
Mouse, keyboard, scanner
Output devices: allow processed data to be exported out of the computer
Printer, monitor, speakers
Processing: working on the data; such as:
Organizing data
Checking data for accuracy
Mathematical or other manipulations on data
Central Processing Unit (CPU): hardware that performs the tasks

7. Programming language:
Special language (like French or German)
Understood by the computer
Tells the computer what to do
Used by a programmer to write a program
Visual Basic, Java, C#, C++, COBOL
Machine language:
Language of the computer
Every “Programmer” language is converted to machine language
Consists of bits on or off only
Compiler or interpreter:
Software that translates programming languages to machine language

8. Components of a computer
Central Processing Unit (CPU)
Internal memory
RAM (Random Access Memory)
ROM (Read Only Memory)
Mass storage devices
Magnetic, optical, and solid-state
Input devices such as keyboard and mouse
Output devices such as monitor and printer

9. Central Processing Unit (CPU)
Often called the brain of the computer
Carries out program instructions ( in memory)
Performs arithmetic and logical operations Arithmetic Logical Unit (ALU)
Controls other computer components (operating system)
Consists of millions of transistors on a single microchip that plug into the motherboard

10. Internal Memory ROM: read-only memory RAM: random-access memory
Contains instructions used by computer during startup
Cannot be altered by computer user
RAM: random-access memory
Is a “scratch pad” for user as he or she works
Can be read from and written to
Operating System/Applications reside

11. Storage categories: internal and external Internal storage:
Main memory, random access memory (RAM)
Located inside the computer system
Volatile: contents are lost when power goes down
External storage:
Persistent: contents are relatively permanent
Floppy drive, hard drive, flash media, magnetic tape
Located outside the computer system

12. Mass Storage Devices Magnetic storage Optical storage
Hard disks, floppy disks, zip drives
Hard disks are internal, others are external
Optical storage
CDs and DVDs
Solid-state storage
Flash drives plug into a USB port

13. Software System Software Application Software Control system resources
Operating systems – Windows, DOS, Linux, UNIX, dll, utilities, drivers
Application Software
Interract with a user
Word Processors (MS Word)
Database Managers (Access)
Spreadsheets (Excel)
Photo Editors
Web browsers, programs (Netscape)

14. What is Programming?
A program is a list of instructions that is executed by a computer to accomplish a particular task.
Creating those instructions is programming by a programmer

15. Using software to translate the program into machine language:
Coding the program:
Select the programming language
Write the instructions
Using software to translate the program into machine language:
Programmers write instructions in English-like high-level languages
Compilers or interpreters change the programs into low-level machine language that can be executed
Syntax errors are identified by the compiler or interpreter

16. Programming Languages
Machine Languages
Assembly Languages
One programmer instruction converted to 1 machine level instruction
ADD A,B
High-level Languages
Looks more like English words and algebraic expressions
Examples of high level languages
Programmer instruction converted to many machine level
ADA BASIC
C++ FORTRAN
COBOL Java
Pascal Visual Basic

17. Machine Language Generation
Programmer written computer code
Programmer written computer code
Translator (Interpreter) Program (browser)
Compiler
Assembler
One Machine Language Instruction
FUNCTION Browsers netscape MS Explorer Javascript PHP ASP
Many machine Language Instructions
.exe file
Execute
Execute
MS Word, Windows XP, MS Excel, Vista, MS Explorer

18. Writing Programs
To write a program in a high-level language, you need:
Appropriate software
A text editor to type and edit program statements
A debugger to help find errors in program code
A compiler or interpreter to translate the program into machine language

19. Error Types
Syntax: the rules governing word usage and punctuation in the language (format, recipe, formula)
Logic errors are more difficult to locate than syntax errors

20. A program must be free of syntax errors to be run, or executed, on a computer
The program will not compile or be translated
A message will point out the offending instruction
To function properly, the logic must be correct
The program will still execute
The output may be incorrect
The program may exit prematurely
The program may ABEND (Abnormal Termination)
The program may execute with no errors/problems

21. Logic
A program must be free of syntax errors to be run, or executed, on a computer
To function properly, the logic must be correct
What’s wrong with this logic for making a cake?

22. Programming Process Seven programming phases: Define the Problem
Outline the Solution
Develop the Outline into an Algorithm
Test the Algorithm for Correctness
Code the Algorithm in a specific language
Run the program on the computer
Document and maintain the program

23. Define the Problem: May be the most difficult phase
Users may not be able to articulate their needs well
User needs may be changing frequently
Programmers may have to learn the user’s functional job tasks
Failure to understand the problem is the major cause of most project failures
If this is not correct – the rest of the project cannot be correct

24. Outline the Solution:
Plan the high-order steps that the program will take
Walk through the logic before coding by desk-checking the logic

25. Develop the Outline into an Algorithm:
Use tools such as flowcharts and pseudocode
Flowchart: a pictorial representation of the logic steps
Pseudocode: English-like representation of the logic

26. Test the Algorithm for Correctness:
Walk through the logic before coding by desk-checking the logic
Make corrections to the Flowchart/Pseudocode as needed

27. Code the algorithm in a specific language:
Select the programming language
Write the instructions
Using software to translate the program into machine language:
Programmers write instructions in English-like high-level languages
Compilers or interpreters change the programs into low-level machine language that can be executed
Syntax errors are identified by the compiler or interpreter

28. Run the program on the computer:
Test for Syntax errors (when compiling)
Test for logic errors by using selected data

29. Document and maintain the program:
Create user documentation
Create technical documentation
Create documentation library
Monitor processing and outputs

30. Syntax Error Cycle

31. Putting the program into production
Testing the program:
Execute it with sample data and check results
Identify logic errors and correct them
Choose test data carefully to exercise all branches of the logic
Putting the program into production
Do this after testing is complete and all known errors have been corrected
May require coordination with other related activities or software

32. Constant: value does not change
Variable: a memory location whose contents can vary; also called an identifier
Each programming language has it own rules for naming identifiers, including:
Legal characters
Maximum length
Use of upper or lower case
Variable name must be a single word, but can be formed from several words
rate, interestRate, interest_rate
Constant: value does not change
Values that do not change while the program is running
Have identifiers, and can be used like variables for calculations, but cannot be assigned new values
Literal: is use of data itself (ex: pi – )

33. Data Types Basic data types: Numeric data Text data Text Numeric
stored by numeric variables
Text data
stored by string, text, or character variables –
surrounded by “ “ (ie. “color”)

34. Types of Data Numeric Data Character data (alphanumerics)
Integer data (whole numbers)
Real (Floating point) data (numbers that have a decimal point)
Note: 5 and 5.0 are stored differently in a computer even though they have the same value. The first, 5 is an Integer but the second, 5.0 is a Real number.
Character data (alphanumerics)
All the characters you can type at the keyboard
The type is String or Character

35. Numeric data types: Integer: whole numbers only
Floating-point: fractional numeric values with decimal points

36. Character data (alphanumerics)
Numeric Data
Integer data (whole numbers)
Real (Floating point) data (numbers that have a decimal point)
Note: 5 and 5.0 are stored differently in a computer even though they have the same value. The first, 5 is an Integer but the second, 5.0 is a Real number.
Character data (alphanumerics)
All the characters you can type at the keyboard
The type is String or Character

37. Concatenation
Concatenation takes two strings and joins them to create a string result
The concatenation operator is symbolized, in pseudocode, with a + sign
Example: if:
String1 = “yellow” and String2 = “duckie”
then the statement:
Set MyFriend = String1 + String2
results in:
MyFriend = “yellow duckie”

38. Binary Machine Language – all data types consist of 1s and 0s
1 bit (0 or 1)
4 bits = nibble
1 byte = 8 bits = 2 nibbles
Is the storage for one character
1 word = 4 bytes
1 K = 1 KB = 1 kilobyte = 1,0240 bytes = 210 bytes
Kilo = 1,000 : 1 KB = 1,000 bytes
1 Meg = 1 megabyte (MB) = 1 million = 1024 KB
1 GB = 1 gigabyte (GB) = 1024 MB = 1,000,000,000
Many people approximate to steps of 1000, not 1024

39. Data Groupings: File
Character: single symbol (letter, number, special symbol)
“A”, “7”, “$”
Field: group of characters forming a single data item
“Smith”
Record: a group of related fields
Customer record containing name and address fields
File: a group of related records
Customer file, containing all customer records

40. Data Groupings: Database
Character: single symbol (letter, number, special symbol)
“A”, “7”, “$”
Field: group of characters forming a single data item
“Smith”
Table: a group of related fields
Customer record containing name and address fields
Database: collection of related tables, that serve the information needs of the organization

41. Using Flowchart Symbols and Pseudocode Statements
Flowchart: pictorial representation of the logic
Pseudocode: English-like representation of the logic
Example:

42. Flowchart input symbol:

43. Flowchart processing symbol

44. Flowchart output symbol:

45. Terminal symbol (start/stop symbol):
Flowlines:
Connect the steps
Show the sequence of statements
Have arrows to show the direction
Terminal symbol (start/stop symbol):
Shows the start and end points of the statements
Lozenge shape

46. Flowchart vs. Psuedocode

47. Back-pointing arrows show statements that will be repeated

48. Infinite loop: a sequence of statements that repeats forever with no escape
Avoid infinite loops by testing for a predetermined value that means “stop processing”
Decision: testing a value
Flowchart decision symbol: a diamond shape, with two flowlines, one for Yes and one for No

49. Sentinel value (or dummy value)
Does not represent real data
Signal to stop
Can be used with input from files or from users
End-of-file (EOF) marker:
Code stored in the file that marks the end of the data
Usually used instead of a sentinel value for file input

50. Flowchart connector symbol:
Marks a logic transfer to another location in the flowchart
Transfer location can be on the same page or on another page
On-page symbol: a circle with a number or letter to identify the matching transfer location
Off-page symbol: a square with a pointed bottom, containing page number and a number of letter to identify the matching transfer location

52. Assignment statement:
Assigns a value to a variable
Variable must appear on the left side, value on the right side of the assignment operator
Right side may be an expression that will be evaluated before storing the value in the variable
Assignment operator: the equal sign (=) in most languages
Variable:
Memory location: has an address and a value
Value (contents) is used for various operations

53. Arithmetic Operations
+ Addition = 5
- Subtraction 7 – 3 = 4
* Multiplication 5 * 4 = 20
/ Division 12 / 3 = 4
^ Exponentiation 2 ^ 3 = 8
% Modulus 14 % 3 = 2

54. Hierarchy of Operations
1st: perform operations inside parentheses (from inside out if more than one)
2nd: perform exponentiation
3rd: do multiplications, divisions, and modulus from left to right (if there are more than one)
4th: do additions and subtractions from left to right (if there are more than one)

55. Example of Hierarchy of Operations
3 * (6 + 2) / 12 – (7 – 5) ^ 2 * 3 = ?
( ) first: = 3 * 8 / 12 – 2 ^ 2 * 3
^ next: = 3 * 8 / 12 – 4 * 3
Leftmost * next: = 24 / 12 – 4 * 3
Division next: = 2 – 4 * 3
Multiply next: = 2 – 12
Subtract last: = -10

56. Relational Operators
Relational operators are the symbols used in the condition to be evaluated in If statements:
= equal to
<> not equal to
< less than
> greater than
<= less than or equal to
>= greater than or equal to

57. Comparison vs. Assignment Operators
The equals sign (=) in this text may have two different meanings. The difference is very significant.
As an assignment operator, the equals sign sets the value of an expression on the right side to the variable on the left side.
As a comparison operator, the equals sign asks the question, “Is the value of the variable on the left side the same as the value of the expression, number, or variable on the right side?”
Many programming languages distinguish between these two operators as follows:
a single equals sign (=) signifies the assignment operator
a double equals sign (==) signifies the comparison operator
This is demonstrated in the examples that follow in the next slides.

58. Logical Operators
Logical operators are used to connect simple conditions into a more complex condition called a compound condition.
AND OR NOT

59. Hierarchy of Operations
Type
Operator
Order Performed
Arithmetic operations
are performed first, in order shown
( ) ^
* / %
+ -
1st parentheses
2nd exponentiation
3rd: multiplication, division, modulus
4th: addition, subtraction
Relational operations
are performed second
= <> < <= > >=
All relational operators have equal precedence
Logical operations
are performed last, in the order shown
NOT
AND OR
1st: NOT
2nd: AND
3rd: OR

60. Two major programming techniques:
Procedural programming
Object-oriented programming
Procedural programming: focuses on the procedures that programmers create
Object-oriented programming: focuses on objects that represent real-world things and their attributes and behaviors
Both techniques employ reusable program modules

61. Annotate the Output
If the output consists of numbers or any data that has no explanatory text with it, you should annotate your output – this means to add some text so the user knows what the output means.