Spring 1999, Computer Org, Assignment 5

Due Monday 4/19 at 5 pm

This is an optional assignment. It may be used to replace a previous assignment. If you decide to do it, then it must be handed in ON TIME.

You must drop off the assignment at my office before 5 pm on Monday 4/19.

1. (3 points) Draw a 4-bit adder where there is no carry propogation delay for any of the 1-bit ALUs. In other words, all the 1-bit ALUs can calculate their correct result without waiting for the other ALUs to complete their additions. The circuit will be more complicated, but faster.
2. (3 points) Draw circuit for a 4-bit incrementer. It is like a counter: on each clock pulse a 1 is added to the total stored in the 4-bit output.
3. (4 points) Mic-2
   • Explain in detail why INVOKEVIRTUAL is only 11 instructions in Mic-2, but 22 instructions in Mic-1. Indicate why some instructions could be combined, and why some instructions could be eliminated altogether.
   • Do the same analysis for ILOAD.
4. (2 poionts) Whenever the ALU does subtraction for unsigned numbers, it inverts the normal carry out bit to set the carry flag. how would this be implemeted in hardware?
5. (2 points) It is not reliable to use the N bit to determine the relative order of two unsigned numbers. Give me an example of subtracting unsigned numbers as follows:
   • Perform A - B where the result is negative and A < B.
   • perform C - B where the result is positive and C < B. B should be the same number as in the first subtraction.
6. (4 points) Mic-3. Figure 4-33 on page 258 shows how the SWAP instruction from Mic-2 would be sequenced in Mic-3.
   • Create a similar table for ILOAD.
   • Create a similar table for IRETURN
7. (2 points) Consider the direc-mapped cache on page 267.
   • What would be the tag and line for the hex address 087F473ADh?
   • If this were a full associative cache, then what would be the tag and the line for the same address?