81.  Assuming all numbers are in 2's complement representation, which of the following numbers is divisible by 11111011? 
Discuss 
Answer: (a).11100111

82.  For a pipelined CPU with a single ALU, consider the following situations 1. The j + 1st instruction uses the result of the jth instruction as an operand 2. The execution of a conditional jump instruction 3. The jth and j + 1st instructions require the ALU at the same time Which of the above can cause a hazard ? 
Discuss 
Answer: (d).All of above

83.  The literal count of a boolean expression is the sum of the number of times each literal appears in the expression. For example, the literal count of (xy + xz') is 4. What are the minimum possible literal counts of the productofsum and sumofproduct representations respectively of the function given by the following Karnaugh map ? Here, X denotes "don't care". 
Discuss 
Answer: (c).(9, 10)

84.  Consider the ALU shown below. If the operands are in 2's complement representation, which of the following operations can be performed by suitably setting the control lines K and C0 only (+ and  denote addition and subtraction respectively) ? 
Discuss 
Answer: (a).A + B, and A  B, but not A + 1

85.  Consider the following circuit composed of XOR gates and noninverting buffers. The noninverting buffers have delays d1 = 2 ns and d2 = 4 ns as shown in the figure. Both XOR gates and all wires have zero delay. Assume that all gate inputs, outputs and wires are stable at logic level 0 at time 0. If the following waveform is applied at input A, how many transition(s) (change of logic levels) occur(s) at B during the interval from 0 to 10 ns ? 
Discuss 
Answer: (d).4

86.  Consider the grammar rule E → E1  E2 for arithmetic expressions. The code generated is targeted to a CPU having a single user register. The subtraction operation requires the first operand to be in the register. If E1 and E2 do not have any common sub expression, in order to get the shortest possible code 
Discuss 
Answer: (b).E2 should be evaluated first

87.  If 73x (in basex number system) is equal to 54y (in basey number system), the possible values of x and y are 
Discuss 
Answer: (d).8, 11

88.  Which of the following addressing modes are suitable for program relocation at run time ? (i) Absolute addressing (ii) Based addressing (iii) Relative addressing (iv) Indirect addressing 
Discuss 
Answer: (c).(ii) and (iii)

89.  Consider the partial implementation of a 2bit counter using T flipflops following the sequence 02310, as shown below. To complete the circuit, the input X should be 
Discuss 
Answer: (d).Q1 ⊕ Q2

90.  The microinstructions stored in the control memory of a processor have a width of 26 bits. Each microinstruction is divided into three fields: a microoperation field of 13 bits, a next address field (X), and a MUX select field (Y). There are 8 status bits in the inputs of the MUX. How many bits are there in the X and Y fields, and what is the size of the control memory in number of words? 
Discuss 
Answer: (a).10, 3, 1024
