Homework 3: Do these instructions work?

• Understand the impact of an instruction set architecture.

• LOAD: load a value from memory into the accumulator
• STORE: store the value in the accumulator to memory
• ADD: add a value from memory to the accumulator
• ADDI: add the immediate encoded in the instruction to the accumulator.
• NEGATE: negate the accumulator (IE 3 becomes -3, -3 becomes 3)
• JUMPNZ: Jump on not zero, if the accumulator is not 0, jump
• IO: If the value of the address is 0, read into the accumulator, if the value of the address is 1, output the accumulator.
• STOP

1. [2 points] Design an instruction format for a 8 bit machine.
2. [1 point] Describe the range of immediate values
3. [1 point] Describe the range of memory addresses.
4. [4 points] Can you write a controlled looping program for this machine? IE, the loop must be able to exit when a condition is reached.
5. [3 points] Compared to WOMBAT would you expect this machine to require more or fewer instructions to execute a loop? Justify your answer.
6. [3 points] Compared to WOMBAT, would you expect the clock cycle to be faster or slower for this machine? Justify your answer.
7. [2 points] What would the impact be of increasing the word size of this machine from 8 to 16 bits?
8. [2 points] What is the impact of removing the ADDI instruction? Could you still write a loop? What would be the cost of this action?
9. [2 points]If you could add one more instruction to this set, what would it be? Why?