Instructions for Lab 5

• Copy LoadableWord.java and MachineI.java to your architecture directory. Copy TestMach.java to your operatingSystem directory.
• Read Chapter 8 of the notes.
• Read about cast.
• Your job is to write one file Machine.java that contains a class Machine. Other than the instance variables, constructors, and get-methods, you will have to write the following methods:
  • fetchInstruction: this method is not in the interface but you will find it useful in implementing other methods. The process of fetching an instruction involves the following steps. First get the word stored in the memory location addressed by the PC. That word better be an instruction (not an address or a data); store it in the IR. Increment the PC.
  • step: This method takes an InsVisitor argument: it simply fetches the current instruction, and asks it to accept the InsVisitor argument.
  • run: This method steps one instruction at a time until a HaltE exception is raised.
  • load: This method accepts a program (represented as an Enumeration of special words called loadableWords) and loads it in memory. Every loadableWord consists of an int address and a Word; it should processed by storing the Word at the memory address. The address of the first loadableWord should be saved in the PC.
• As usual you compile as follows:

  javac duckMachine\architecture\*.java
  javac duckMachine\operatingSystem\*.java
  

• Test your code by running:

  java duckMachine.operatingSystem.TestMach