MCQs on Microprocessor


Page 12 of 19. Go to page
01․ The 8085 microprocessor uses a crystal of frequency 6.25 Mhz. The T-state value is
320ns
640ns
960ns
1280ns

We know Now,

02․ When an 8085 microprocessor is reset, the address bus contains
0000H
002CH
0043H
003CH

When an 8085 microprocessor is reset, the address bus contains 0000H.

03․ In an 8085 microprocessor based system, the contents of SP are 1000H, PUSH B instruction will transfer the contents of registers B & C respectively for memory locations
0FFF H and 0FFE H
0FFE H and 0FFF H
1000 H and 0FFF H
1000 H and 1001 H

Stack pointer indicates the top of the stack memory. If data are to be moved in stack memory then those will start to be stored from above the address contained by stack pointer. In this problem stack pointer contains 1000 H. So when PUSH B instruction is given data will start to be stored from 0FFF H, 0FFE H, 0FFD H onwards.

04․ In an 8085 microprocessor based system, the contents of SP are 2000H. POP H instruction will transfer the contents of memory location
2001H and 2002H to H and L registers respectively
2001H and 2000H to H and L registers respectively
2000H and 1FFFH to H and L registers respectively
2000H and 1999H to H and L registers respectively

The content of 2001 H will be stored into H and content of 2000 H will be stored in L.

05․ PUSH B instruction in 8085 microprocessor causes
the contents of register B only to be copied in the stack
the contents of register B & C to be copied in the stack
the contents of registers B & C to be transferred in the stack and and the registers get cleared
registers B & C to be cleared

PUSH B instruction allows to copy the contents of register pairs B & C to the stack

06․ SUB A instruction in 8085
reset carry and sign flags
reset zero and parity flags
sets zero and sign flags
sets zero and carry flags

SUB R instruction allows to subtract the content of register R from Accumulator (A). Likewise, SUB A instruction will allow to subtract the content of Accumulator form Accumulator. Hence, carry and sign flags will be reset.

07․ In 8085 microprocessor , let the accumulator contains the value 0AH and register C contains the value 05H. After CMP C instruction is executed, the
zero and carry flags will be set
zero and carry flags will be reset
zero flag will be set and carry flag will be reset
zero flag will be reset and carry flag will be set

CMP C instruction allows to subtract the content of Register C from Accumulator. So, in the given problem 05 H will be subtracted from 0AH and results 05 H whose binary form is (0000 0101)2. As content of Accumulator is greater than register C then both the carry and zero flag are reset.

08․ Which of the data transfer is not possible in microprocessor
memory to accumulator
accumulator to memory
memory to memory
I/O device to accumulator

In 8085 microprocessor memory to memory data transfer is not possible.

09․ In 8085 microprocessor, in response to RST 7.5 interrupts the execution is transferred to memory location
0000H
002CH
0034H
003CH

The vector address of RST 7.5 is hexadecimal equivalent of . So, in response to RST 7.5 interrupts the execution is transferred to memory location 003CH.

10․ In 8085 microprocessor which one of the following statement is wrong
there is a pin available for serial input
there is a pin available for serial output
serial I/O is possible through SIM and RIM instruction
serial I/O is not possible

8085 microprocessor has two signals to implement serial data transmission SID(Serial Input Data) and SOD(Serial Output Data).Serial I/O is also possible through SIM (Serial output data) and RIM (Serial input data) instruction in 8085 microprocessor.

<<<1011121314>>>