8085 Microprocessor MCQ

61. Assume that the accumulator and the register C of 8085 microprocessor contain respectively F0 H
and OF H initially. What will be the content of accumulator after execution of instruction ADD C?

1. 00 H
2. FF H
3. EF H
4. FE H

62. It is desired to multiply the numbers 0A H by OB H and store the result in the accumulator. The numbers are available in registers B and C respectively. A part of the 8085 program for this purpose is given below:

MVI A, OO H
Loop; ………..

            ………..

            ………..
HLT END

The sequence of instruction to complete the program would be

1. JNZ LOOP; ADD B, DCR C
   
2. ADD B; JNZ LOOP; DCR C
   
3. DCR C; JNZ LOOP; ADD B
   
4. ADD B; DCR C; JNZ LOOP

63. Find the content of the accumulator after the execution of the following program:

MVI A, F0 H
ORI FF H
XRI F0 H

1. 00 H
2. F0 H
3. 0F H
4. FF H

64. The following program starts at location 0100 H

LXI SP, 00FF
LXI H, 0701 H
MVI A, 20 H
SUB M

The content of accumulator when the program counter reaches 0107 H is

1. 20 H
2. 02 H
3. 00 H
4. FF H

65. The difference between 8085 instructions RST n and PCHL is

1. RST n is equivalent to a sub-routine call while PCHL is equivalent to unconditional branch.
2. RST n uses direct addressing while PCHL uses register indirect addressing.
3. RST n is a software interrupt while PCHL simulates a hardware interrupt
4. RST n resets the processor while PCHL restarts the processor.

66. The content of accumulator are 70 H. Initially all flags are zero. What will be values of CY and S after executing instruction RLC?

1. CY = 0 and S = 0
2. CY = 1 and S = 1
3. CY = 1 and S = 0
4. CY = 0 and S = 1

67. A software delay subroutine is written as given below:

DELAY:           MVI H, 255D H
MVI L, 255D H
LOOP:             DCR L
JNZ  LOOP
DCR H
JNZ LOOP

How many times DCR instruction will be executed?

1. 255
2. 510
3. 65025
4. 65279

68. What is content of accumulator of 8085 microprocessor after the execution of XRI F0 H instruction?

1. Only the upper nibble of accumulator is complemented
2. Only the lower nibble is complemented
3. Only the upper nibble is reset to zero
4. Only the lower nibble is reset to zero

69. The 8085 programming manual says that it takes seven T states to fetch and execute the MOV instruction. If the system clock has a frequency of 2.5 MHz, how long is an instruction Cycle?

1. 2.8 s
2. 2.5ns
3. 2.8 ns
4. 2.8 μs

70. The instruction PCHL, in 8085 is used for

1. Load PC with contents of HL.
2. Load HL with contents of memory location pointed by PC.
3. Load HL with contents of PC
4. Load PC with the contents of memory location pointed by HL pair.