Indian Institute of Technology Madras (IIT-M) 2000 A.M.I.E.T.E Computer Science

ans by completing the subsequent statement in your ans book:
By combining signals
ii. Consider the subsequent 8085 program segment, where registers B and C contain BCD
values:
Si: MVI A, 99H
MVI D, OOH
SUB C
ADD B
DAA
S2: JC S3
Memory Address Machine Code
3050 DA
3051 09
MOV E, A
MVI A, 99H
SUB E
MOV E, A
JZ S4
MVI D, FFH
JMP S4
S3: INC A
DAA
MOV E, A
S4
(a) For the 2 pairs (B = 44, C = 25) and (B = 33, C = 46) at Si,
(i) obtain the values in register A when control reaches S2.
(ii) obtain the values in registers D and E when control reaches S4.
(b) What, in general, is the value of D and E as a function of B and C when control reaches S4.
6. An instruction pipeline has 5 stages where every stage takes two nanoseconds and all
instructions use all 5 stages. Branch instructions are not overlapped, i.e., the instruction
after the branch is not fetched till the branch instruction is completed. Under ideal conditions.
(a) compute the avg. instruction execution time assuming that 2O% of all instruction
executed are branch instructions. Ignore the fact that a few branch instructions may be
conditional.
(b) If a branch instruction is a conditional branch instruction, the branch need not be taken. If
the branch is not taken, the subsequent instructions can be overlapped. When 8O/c of all branch
instructions are conditional branch instructions, and 5Q% of the conditional branch
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instructions are such that the branch is taken, compute the avg. instruction execution
time.
7. Suppose a stack implementation supports, in addition to PUSH and POP, an operation
REVERSE, which reverses the order of the elements on the stack.
(a) To implement a queue using the above stack implementation, show how to implement
ENQUEUE using a single operation and DEQUEUE using a sequence of three operations.
(b) The subsequent postfix expression, containing single digit operands and arithmetic operators
+ and *, is evaluated using a stack.
52*34+52**+
Show the contents of the stack.
(i) After evaluating five two * three four +
(ii) After evaluating five two * three four + five 2

Earning:   Approval pending.