Problem Set Number 2
Computer Science 471

Due by 5 PM, Monday Oct. 2, 2000

1. Problem 4.10 from the Patterson & Hennessy text.

2. Problem 4.14 from the text. (Beware: the address-displacement field of loads and stores is a signed, 2's-complement number.)

3. Problem 4.18 from the text.

4. Let x = 10010.1101 and y = 00110011.1 and z = -111100.10101 be the sign-and-magnitude representations in base 2 of three numbers. Show exactly how x, y, and z would be represented in the IEEE single-precision floating-point format. Show all the bits, just as they would appear in a MIPS register or memory word.

5. Show the steps involved in the single-precision floating-point addition of x and y from question 4. Use binary operations, and show all the partial results along the way. The operands must start out in IEEE format. This question does not ask you to design any hardware, just to show the computational steps, like ``shift significand'' and ``normalize'' and ``round'' and things like that. Assume that the rounding rule is: round to the nearest representable number, and round to the even one if the result is exactly half-way between the two nearest numbers. Show all the bits of the result in IEEE format, just as in question 4.

6. (counts double) Problem 4.52 from the text, with the following changes. First, assume that the intermediate terms M15, M14, and so on, have been properly shifted and are stored in 32-bit form. Second, in the final paragraph of the problem statement, change the widths of the adders from 16 bits to 32 bits (first line and next-to-last line of the final paragraph).

These changes should help you see the structure more clearly, but please be aware that there is no single correct answer to this question. For a tiny tiny amount of extra credit, show how wide each carry-save adder must be.