Self-Test Questions

Suggested Projects

1. Matrix Multiplication:   Given two matrices A_ij and B_jk the product C_ik can be calculated with the following equation:

   

   Write a program that multiplies the following matrices together and stores the results in a new matrix. Print the resulting matrix values to the console.

   

2. Modify Histogram Program:   Modify the Histogram program given in example 8.8 so that it can count the occurrence of the digits 0 through 9 and the punctuation marks period ‘.’, comma ‘,’, question mark ‘?’, colon ‘:’, and semi-colon ‘;’.

3. Computer Simulator:   You are a Java developer with a high-tech firm doing contract work for the Department of Defense. You company has won the proposal to develop a proof-of-concept model for an Encrypted Instruction Set Computer System Mark 1. (EISCS Mk1) Your job is to simulate the operation of the EISCS Mk1 with a Java application.

• Supporting Information:   The only language a computer understands is its machine language instruction set. The EISCS Mk1 is no different. The EISCS machine language instruction set will consist of a four-digit integer with the two most significant digits being the operation code (opcode) and the two least significant digits being the operand. For example, in the following instruction...

  

• ...the number 11 represents the opcode and the number 33 represents the operand. The following table lists and describes each EISCS machine instruction.

• Sample Program:   Using the instruction set given in table 8-3 you can write simple programs that will run on the EISCS Mk1 computer simulator. The following program reads two numbers from the input, multiplies them together, and writes the results to the console.

  Table 8-3: EISCS Machine Instructions

  Opcode	Mnemonic	Description
  		Input/Output Operations
  10	READ	Reads an integer value from the console and stores it in memory location identified by the operand.
  11	WRITE	Writes the integer value stored in memory location operand to the console.
  		Load/Store Operations
  20	LOAD	Loads the integer value stored at memory location operand into the accumulator.
  21	STORE	Stores the integer value residing in the accumulator into memory location operand.
  		Arithmetic Operations
  30	ADD	Adds the integer value located in memory location operand to the value stored in the accumulator and leaves the result in the accumulator.
  31	SUB	Subtracts the integer value located in memory location operand from the value stored in the accumulator and leaves the result in the accumulator.
  32	MUL	Multiplies the integer value located in memory location operand by the value stored in the accumulator and leaves the result in the accumulator.
  33	DIV	Divides the integer value stored in the accumulator by the value located in memory location operand.
  		Control and Transfer Operations
  40	BRANCH	Unconditional jump to memory location operand.
  41	BRANCH_NEG	If accumulator value is less than zero jump to memory location operand.
  42	BRANCH_ZERO	If accumulator value is zero then jump to memory location operand.
  43	HALT	Stop program execution.

  Memory Location	Instruction/Contents	Action
  00	1007	Read integer into memory location 07
  01	1008	Read integer into memory location 08
  02	2007	Load contents of memory location 07 into accumulator
  03	3208	Multiply value located in memory location 08 by value stored in accumulator. Leave result in accumulator
  04	2109	Store value currently in accumulator to memory location 09
  05	1109	Write the value located in memory location 09 to the console
  06	4010	Jump to memory location 10
  07
  08
  09
  10	4300	Halt program

• Basic Operation:   This section discusses several aspects of the EISCS computer simulation operation to assist you in completing the project.

• Memory:   The machine language instructions that comprise an EISCS program must be loaded into memory before the program can be executed by the simulator. Represent the computer simulator’s memory as an array of integers 100 elements long.

• Instruction Decoding:   Instructions are fetched one at a time from memory and decoded into opcodes and operands before being executed. The following code sample demonstrates one possible decoding scheme:

   instruction = memory[program_counter++]; operation_code = instruction / 100; operand = instruction % 100;

Hints:

• Use switch/case structure to implement the instruction execution logic

• You may hard code sample programs in your simulator or allow a user to enter a program into memory via the console

• Use an array of 100 integers to represent memory