1. Which one of the ALU operations listed below is performed to support the beq instruction on our MIPS single-cycle datapath?

a) AND
b) Sign extension
c) Subtraction
d) Addition
e) OR

2. For which of the instructions listed below will the 4-bit ALU control bits = 0110?

a) add
b) subtract
c) slt
d) AND
e) OR

3. What is the required 4-bit ALU control pattern for the ADD instruction?

4. Suppose that a beq instruction resides at memory address 0x08000000 and that the rightmost 16 bits within the machine code for the beq contains the value 0xAA. To what value (expressed in hex) would the PC be set if the zero flag=1 when the beq instruction is executed?

5. Assume that the breakdown of executed instructions is as follows:
Add 20%
Addi 20%
Not 0%
Beq 25%
Lw 25%
Sw 10%

a. In what fraction of all cycles is the data memory used? Show your work.

b. In what fraction of all cycles is the input of the sign-extend circuit needed? Show your work.

6. Consider the following instruction

ADD $s5, $s6, $s7

a. What are the values of the control signals generated by the control unit in figure 4.17?
b. What resources (blocks) perform a useful function for this instruction?
c. Which resources (blocks) produce outputs, but their outputs are not used?
d. Which resources produce no outputs for this instruction?

7. Assume that the various devices or components within our MIPS single cycle datapath as shown in Figure 4.20 require the time indicated in the table below to perform their function:

Unit        Time in nano-seconds
Memory              12
Register file        2
Sign extension       2
ALU                6
Adder                3
Multiplexer        1

Based on this table, what is the minimum time (in nano-seconds) required to execute the sw instruction?

8. A MIPS single cycle processor fetches the following instruction word


a) What are the ALU control unit’s inputs for this instruction?
b) What are the data input values to the ALU?

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These solutions may offer step-by-step problem-solving explanations or good writing examples that include modern styles of formatting and construction of bibliographies out of text citations and references. Students may use these solutions for personal skill-building and practice. Unethical use is strictly forbidden.

Ref. book pp. 260 – 1st paragraph : “ALUOp indicates whether the operation to be performed should be […]subtract (01) for beq”.
The correct choice is c) Subtraction.

Ref. book pp. 259 – the table.
The correct choice is b) Subtract.

Ref. book pp. 259 – also the same table as above.
The correct ALU 4-bit pattern for “add” instruction is 0010....

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