NEHRU JARPULA

MPMC : MICROPROCESSORS AND MICROCONTROLLERS

MULTIPLE CHOICE QUESTION AND ANSWERS

MICROPROCESSORS AND INTEFACING.

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1. Single step command in DEBUG execution is enabled by _________ flag

A) Interrupt Flag
B) Trap Flag
C) Directional Flag
D) Sign Flag

Answer is B)

Trap Flag (T) – This flag is used for on-chip debugging. Setting trap flag puts the microprocessor
into single step mode for debugging. In single stepping, the microprocessor executes a instruction
and enters into single step ISR.
If trap flag is set (1), the CPU automatically generates an internal interrupt after each instruction,
allowing a program to be inspected as it executes instruction by instruction.
If trap flag is reset (0), no function is performed.

2. The instruction that used for terminating MASM program is ___

A) INT 21H
B) INT 4CH
C) INT 3H
D) INT 2H
Answer is C)
INT 3 is a special one byte interrupt that is inserted by debuggers at the instruction
where the user has set a breakpoint to occur. When it's hit, the interrupt handler breaks
into the debugger and then replaces the original instruction so that execution can proceed
when the user is ready.

3. 8086 MPU has the _________ bit memory mapping and ____________ bit IO mapping

A) 20 , 16
B) 16 , 8
C) 16 , 16
D) 16 , 20
Answer is A)
• It is a 16 bit µp.
• It can support upto 64K I/O ports.
• 8086 has a 20 bit address bus can access upto 2^20 memory locations ( 1 MB) .

4. The 8051 has ________ 16-bit counter/timers.

A) One
B) Two
C) Three
D) Four

Answer is B)

The 8051 has two timers, Timer 0 and Timer 1.
They can be used as timers or as event counters. Both Timer 0 and Timer 1 are 16-bit wide.

5. 8051 series has how many 16 bit registers?

A) Three
B) Two
C) One
D) zero

Answer is B)

8051 series has two 16 bit registers DPTR and PC.

6. The expansion of DAA is_____

A) Decimal Adjust after Addition
B) Decimal Adjust before Addition
C) Decimal Adjust Accumulator
Decimal Adjust Auxiliary

Answer is A)

DAA stands for Decimal Adjust after Addition

7. On power up, the 8051 uses which RAM locations for register R0- R7

A) 00-2F
B) 00-4F
C) 00-7F
D) 00-07

Answer is D)

On power up register bank 0 is selected which has memory address from 00H-07H.

8. . __________ processor is first introduced by the Intel in 1971.

A) 8080
B) 8008
C) 4004
D) 4040

Answer is C)

The Intel 4004 is a 4-bit central processing unit (CPU) released by Intel Corporation in 1971.
It was the first commercially produced microprocessor, and the first in a long line of Intel CPUs.

9. If the EA(active low) signal is grounded then the execution______

A) directly start from main memory
B) directly start from 16 bit address in main memory
C) directly start from 16 bit address in program memory
D) directly start from RAM

Answer is C)

If EA(active low) signal =1, then the execution starts from an internal EPROM or flash RAM address 000H,
can continue upto FFFH address and then for higher addresses it will go into external memory.

10. Which of the following registers are not available in 8086 microprocessor?

A) General purpose register
B) Segment registers
C) Pointer and Index register
D) Non of the above

Answer is D)

General purpose register , Segment registers , Pointer and Index register are present in 8086 MP
So the answer is: Non of the above