Boolean Logic, Algorithms,
Programs, and Basic Scratch
Programming
Boolean Logic
ULM/HHIM Summer Program
Project 3, Day 4, Part 1
6/8/2011
Paul D. Wiedemeier, Ph.D.
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6/8/2011
Boolean Logic
• AND, OR, and XOR are
binary Boolean operators.
• NOT is a unary Boolean
operator.
• When searching computer databases,
including keyword searching of the online
catalog, these sets are controlled by use of
Boolean operators AND, OR, XOR, and
NOT.
Paul D. Wiedemeier, Ph.D.
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Boolean Logic
• The principle of Boolean logic lets you
organize concepts together in sets.
6/8/2011
Paul D. Wiedemeier, Ph.D.
Operator
Result
----------------------------bit AND bit
bit
bit OR bit
bit
bit XOR bit
bit
NOT bit
bit
• All operate on binary
number(s), based on bit
position, or two bits.
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Boolean Logic
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Boolean Logic
• An AND Boolean operator requires two
inputs
• AND truth table
– Inputs are also called operands.
• Outputs ‘True’ or ‘1’ if and only if both
inputs are ‘True’ or ‘1’
• AND graphic symbol
– “AND gate”
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Boolean Logic
Boolean Logic
• An OR Boolean operator requires two
inputs.
• OR truth table
• Outputs ‘True’ or ‘1’ if any one or both
inputs are ‘True’ or ‘1’.
• OR graphic symbol
– “OR gate”
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Boolean Logic
Boolean Logic
• An Exclusive OR (XOR) Boolean operator
requires two inputs.
• XOR truth table
x
y
x XOR y
---------------------0
0
0
0
1
1
1
0
1
1
1
0
• Outputs ‘True’ or ‘1’ if only one of the
inputs is ‘True’ or ‘1’.
– One input is ‘True’, or the other input is ‘True’,
but both are not ‘True’
• XOR graphic symbol
– “XOR gate”
• Symbolized by circle plus sign: x ⊕ y
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Boolean Logic
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Boolean Logic
•
• A NOT Boolean operator requires a single input.
NOT truth table
– Input combinations on the left
• Inverts the value of the input.
– Output of function on the right
•
• Symbolized by a tic or overbar: x’, x
NOT graphic symbol
– “NOT gate”
– Triangle with little circle
indicates inversion
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2
http://en.wikipedia.org/wiki/Algorithm
Algorithms
• In mathematics, computer science, and
related subjects, an algorithm is an effective
method for solving a problem expressed as
a finite sequence of instructions.
Algorithms
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Algorithms
• Algorithms are similar to blueprints.
– Architects create blue prints, which are used by
construction worker to erect buildings.
– System analysts create algorithms, which are
used by computer programmers to create
programs.
• How the instructions are arranged and the
order in which they occur defines a
computer programs semantics.
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Algorithms
• Algorithms are comprised of several
human readable instructions, called pseudo
code, that describe the execution of a
computer program.
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Programming Exercise 1
• Read the directions for Programming
Exercise 1, which you will find in your
folder.
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Paul D. Wiedemeier, Ph.D.
Programs
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Programs
• Though programs are constructed from
algorithms, they are written using a specific
programming language.
– The human readable instructions are converted
into the instructions from a programming
language.
6/8/2011
Paul D. Wiedemeier, Ph.D.
LISP:
(print “Hello World”)
Java:
System.out.print(“Hello World”);
FORTRAN:
WRITE (6,7)
7 FORMAT(13H HELLO, WORLD)
Pascal:
writeln('Hello World');
C:
print(“Hello World”)
Scratch:
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Programs
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Programs
• Basic program operation
• The specific instructions within a
programming language defines the syntax
of a program.
– Obtain input from the user, or from a file, or from both.
• Verify that the input is valid.
• Today, there literally hundreds of
programming languages available for use.
– Process the input to create output.
• Use the correct programming language to solve the
problem at hand.
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– Display the output to the computer's screen and/or store
the output in a file.
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Programs
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Programs
• All programs can be constructed from one
of three types instructions
• Examples of sequential instructions
– Capturing input from the user
– Displaying output to the computer screen
– Assigning a value to a variable
– Performing a mathematical computation
– Sequential instructions
– Selection instructions
– Repetition instructions (i.e. loops)
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Programs
Programs
• Examples of selection instructions
• Examples of repetition instructions
– If (some condition is true), then
– While (some condition is true)
• execute some instructions.
Pre-Test Loop
• Execute some instructions.
– If (some condition is true), then
– Execute some instructions
• execute some instructions,
• While (some condition is true)
Post-Test Loop
– else
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• execute some Paul
other
instructions.
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Programs
• Examples of repetition instructions
Basic Scratch Programming
– Execution of some instructions
Post-Test Loop
• Until (some condition is false)
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6/8/2011
Basic Scratch Programming
Paul D. Wiedemeier, Ph.D.
Basic Scratch Programming
• Scratch is a fairly new programming language
developed by the Lifelong Kindergarten Group at
the MIT Media Lab.
• Locate the Scratch
icon on your
computer’s desktop.
• What makes it unique from older languages is that
it is graphical.
• Double click the
Scratch icon to
execute the Scratch
project development
environment.
– The program instructions look like Lego blocks and
you “snap” them together in a particular sequence to
create a program.
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File Save
File Open
Green Flag
Program Execute
Programming Exercise 2
Different
Instructions
Stage
• Read the directions for Programming
Exercise 2, which you will find in your
folder.
Sprite
Blocks
Pallete
Script Area
Sprite List
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Programming Exercise 3
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Programming Exercise 4
• Read the directions for Programming
Exercise 3, which you will find in your
folder.
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Paul D. Wiedemeier, Ph.D.
• Read the directions for Programming
Exercise 4, which you will find in your
folder.
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