Reference no: EM132874873

Introduction to Little Man Computer

Task 1 -Familarising yourself with LMC

This task is for you to practice and get acquaint with the LMC features, no need to submit anything.

2. LMC is now ready for you. The interface is simple and self-explanatory. Try clicking on HELP button to find more information about this CPU simulator help page.

3. There are 10 program examples come with this simulator which can be selected from SELECT dropdown list.

4. The Assembly Language Code section is where you write a program code on it. Once coding is done, click Submit button to submit the code to LMC. You can click RUN button to execute the program. A step by step execution (one instruction at a time) can be achieved by clicking on STEP button. RESET button is used to put the CPU back to its initial state, where the value of the Program Counter and that of the Accumulator will be reset to 0.

5. STOP is a toggle button. When a program is executing, pressing this button will pause the program execution, pressing a gain to continue executing the program.

6. Rather than writing program code directly on Assembly Language Code area, you can also use a text editor such as NotePad to write your program code on your computer. Use LOAD button to load your program code from your computer to LMC and run it.

7. OPTIONS contains a list of options that can be used to control the operation of LMC.

8. CPU is located between Assembly Language Code and RAM sections. This simple CPU contains a Program Counter (PC) to hold/point to the next memory address/location, an Instruction Register (IR) to hold an instruction op-code fetched from a memory address, an Accumulator to hold value during CPU operation.

9. Now, you may select an example code from SELECT button and try running the program. The operation speed can be adjusted by clicking on <<button (slower) or >> button (faster)

Task 2 - Writing a simple program

1. Read and understand the sample LMC program below. Take special consideration on the program structure. The following program demonstrates the use of LMC assembly language to add an input value to the constant value -1. Note that lines starting with "//" and characters to the right of program statements are considered comments, and are ignored by the LMC.

// A sample LMC assembly language
// to add a number to the value -1
INP// Input number to be added
ADDVALUE //Add value stored at address VALUE to
// input
OUT// Output result
HLT// Halt (program ends here)
VALUEDAT -001// Data value

2. Enter the program code above into the Assembly Language Code section, then Submit and run the program in ‘default normal' speed and then in ‘default slow' - using OPTIONS to select, assume number 10 was entered as an input value. Run the program again but using STEP button. Take a screenshot of each execution mode.

3. Observe and record the results, registers, and memory contents after the program execution has finished.

4. Which program execution mode do you prefer when you want to study the program operation in details for debugging purpose?
Task 3.

1. Draw side-by-side flow diagrams that show how the Little Man Computer executes a store instruction and the corresponding CPU fetch-execute cycle.