WEB-BASED LEARNING TOOLS ON MICROPROCESSOR FUNDAMENTALS FOR A FIRST-YEAR ENGINEERING COURSE

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WEB-BASED LEARNING TOOLS ON MICROPROCESSOR
FUNDAMENTALS FOR A FIRST-YEAR ENGINEERING COURSE

• By
• Jucain Butler

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Outline of Presentation

• Introduction
• Demo
• Student Responses
• Inside the Simulator
• Conclusion

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Introduction

• WWW has changed how teaching occurs
• Virtual labs
• limited resources
• physical space restrictions
• The Tutorial
• A series of surveys, quizzes, references and
  interactive programs that simulates how a
  computer based on Feymans File Clerk and one
  based on the LEGO RCX executes a program.

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What is the RCX
3 input Sensors
3 output Motors

• 32 16-bit registers
• datalog
• Virtual machine
• Infrared transceiver
• programmable in NQC

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Maxfinder

• Developed web-based tutorial to enable students
  to understand what goes on internally in a
  computer for program like the maxfinder

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Previous Work on LEGO in the classroom

• Seymour Papert at MIT -- LOGO
• Fred Martin at MIT - programmable brick
• CEEO at Tufts K-12 education
• Dave Baum of Motorola NQC

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How students proceed through the tutorial

Pre-survey
Read reference page
Interactive demo W/ simulator
Take quiz
Post-survey
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Outline of Demonstration

• Arithmetic Instructions Module
• detailed look from students viewpoint
• Control and Input/Output Instruction Module
• introduces sensors, motors, control statements
• MaxFinder Module

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Arithmetic Operation Reference Page

• Arithmetic instructions perform arithmetic
  operations with 2 operands that overwrite the
  value of the first operand with the result.  They
  always go to the next sequential address for next
  instruction.  For the RCX processor, the
  arithmetic instruction format is composed of five
  pairs of hexadecimal digits (one byte each).  

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Arithmetic Operations Reference Page -- RCX

• 1. The first byte represents one of five
  operations.
• 1)     14 (setv)- stores a value in the
  destination register
• 2)     24 (sumv)- adds operand 1 to operand 2
• 3)     34 (subv)- subtracts operand 2 from
  operand 1
• 4)     44 (divv)- divides operand 2 into operand
  1
• 5)     54 (mulv)- multiplies operand 1 to operand
  2 
• 2. The second byte is the index (or register
  number) of the register that holds operand 1 and
  is the index of the destination register that
  stores the result. 
• 3. The third byte represents one of three types
  for operand 2.
• 1)         0 the value of operand 2 is stored
  in a variable register
• 2)         2 the value of op 2 is immediately
  provided by the next two bytes
• 3)         9 the value of operand 2 is provided
  by a sensor 
• 4. The fourth byte is the least significant byte
  of argument to the second operand. 
• 5. The fifth byte is the most significant byte of
  argument to the second operand. (Note that the
  last two bytes combine to form a two byte integer
  that together represent the argument to the
  second operand.  

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Arithmetic Operations Reference Page -- FC

• 1. The first byte represents one of three
  operations.
• 1)     14 (input)- input value from the scrollbar
  into the register
• 2) 21 (output)- output the value from the
  register to the screen
• 3) 24 (add)- add contents of first register
  to the second
• 4)     34 (sub)- subtract contents of first
  register from second
• 5)     44 (div)- divide contents of second
  register into the first
• 6)     54 (mult)- multiply contents of first
  register by the second
• 2. The second byte is the index (or register
  number) of the register that holds operand 1 and
  is the index of the destination register that
  stores the result. 
• 3. The third byte represents the second operand.

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Arithmetic Operations Reference Page -- RCX
Assembly Operation Machine code
sum v0, v2 v0 v0 v2 24 00 00 02 00
set v2,0x1A5 V2 0x1A5 14 02 02 A5 01
set v7, input(1)A V7sensor val port1 14 07 09 01 00
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Arithmetic Operations Reference Page-- FC
Instruction Operation Machine code
add v0, v2 v0 v0 v2 24 00 02
input v2 V2 input value Input 2
mult v9, v10 V9 v9 x v10 54 09 10
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Proceed to demo

• DEMO

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Results and Student Responses

• Post-Quiz Survey
• How helpful was the learning tool?
• What did the students learn?
• Student suggestions about the tutorials
  strengths and weaknesses
• Over 300 students responded

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Quotes from Student Responses

• It was useful in understanding the underlying
  task the RCX performs to process our NQC
  commands.
• It was very helpful, and I believe we should
  have been required to do this before the Scanner
  project.

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Quotes from Student Responses contd

• I found it interesting to see how high-level
  code works as machine code.
• I was confused by some of the terminology and
  it would have been helpful to have someone there
  to explain.

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Quotes from Student Responses contd

• I think that the online tutorial is a useful
  tool but could become overused by professors.
  This may lead to excessive information for the
  students, and the professors not teaching.

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Graph of Student Responses

• 1 - not helpful
• 2 - a little helpful
• 3 somewhat helpful
• 4 very helpful

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Inside the Simulator

• Approach
• Generic simulator
• Customizing for a particular example
• Implementation
• Java applet
• Object oriented
• Components encapsulated as classes
• Take advantage of inheritance
• how it is customized to a particular demo

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Simulator Organization
Boxes correspond To major classes In Java applet
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Major Classes and Methods

• RCXSimulator Class
• Program Class
• Interpreter Class
• RegisterFrame Class

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RCXSimulator Class

• accept a program, step or run through the
  execution of that program, and displaying the
  state
• an abstract class that inherits from the APPLET
  class
• important methods
• init ()  - initialize variables and instantiate
  instances of major GUI classes
• run() - if the run button is pushed, execute the
  next instruction until the end
• actionPerformed() - perform function based on
  which control button is selected
• abstract int getTheProgram() - get the array of
  bytecodes

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Interpreter Class

•  
• The Interpreter class interprets the bytecodes
  and implements the entire instruction set
• This class is the data type of a variable and is
  instantiated in the RCXSimulator class
• Important Methods
• synchronize executeNextInstruction() - chooses
  from a case statement based on the opCode a
  method which interprets the next instruction.
  it is synchronized because executing an
  instruction is an indivisible act  
• -- this methods that interpret the bytecodes for
  the complete instruction set
• executePWR()
• executeDIR()
• executeSETV()
• executeJUMPL()       
• executeSUMV()     
•  

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Program Class

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• The Program class supplies the RCXSimulator class
  with a programs bytecode and gives the applet
  its personality
• This class inherits from the RCXSimulator class
  and implements its abstract methods
• Important Methods
• getTheProgram() - returns the array of bytecodes
  that constitute a specific program
• getbytecodeMnemonics() - returns the array of
  String that make up the bytecodes mnemonics
• getAppletTitle() - returns the title of the
  applet as a string
•  

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Code Statistics

• There are 24 Classes
• There are 3821 lines of code
• Sensor has 50 lines
• RCXSimulator has 591
• Interpeter has 1301 lines
• Java Class Package Libraries
• AWT
• Applet
• Thread

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Conclusions major contributions

• An effective online tutorial with simulator using
  WebCT
• A simulator for the RCX
• Impacted the education of 300 students

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Conclusions - Findings

• Effective as indicated by quiz survey results
• Useful as a supplement to an introductory
  engineering course
• Some aspects are too technical

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Future Work

• Future
• Increase functionality
• A model approach to other Domains
• Chemical Engineering
• Nano Technology