MCQOPTIONS
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MCQOPTIONS
This section includes 133 Mcqs, each offering curated multiple-choice questions to sharpen your Digital Electronics knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
This program code will be executed continuously: |
| A. | True |
| B. | False |
| Answer» B. False | |
| 2. |
This program code will be executed once: |
| A. | True |
| B. | False |
| Answer» C. | |
| 3. |
The contents of the accumulator after this operation MOV A,#0BH ANL A,#2CH will be |
| A. | 11010111 |
| B. | 11011010 |
| C. | 00001000 |
| D. | 00101000 |
| Answer» D. 00101000 | |
| 4. |
When the 8051 is reset and the line is LOW, the program counter points to the first program instruction in the: |
| A. | internal code memory |
| B. | external code memory |
| C. | internal data memory |
| D. | external data memory |
| Answer» C. internal data memory | |
| 5. |
This program code will read data from port 0 and write it to port 2, and it will stop looping when bit 3 of port 2 is set: |
| A. | True |
| B. | False |
| Answer» B. False | |
| 6. |
The following program will receive data from port 1, determine whether bit 2 is high, and then send the number FFH to port 3: READ: MOV A,P1 ANL A,#2H CJNE A,#02H,READ MOV P3,#FFH |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7. |
When the 8051 is reset and the line is HIGH, the program counter points to the first program instruction in the: |
| A. | internal code memory |
| B. | external code memory |
| C. | internal data memory |
| D. | external data memory |
| Answer» B. external code memory | |
| 8. |
The following command will copy the accumulator to the location whose address is 23H: MOV 23H,A |
| A. | True |
| B. | False |
| Answer» B. False | |
| 9. |
The contents of the accumulator after this operation MOV A,#2BH ORL A,00H will be: |
| A. | 1B H |
| B. | 2B H |
| C. | 3B H |
| D. | 4B H |
| Answer» C. 3B H | |
| 10. |
The following program will cause the 8051 to be stuck in a loop: |
| A. | True |
| B. | False |
| Answer» C. | |
| 11. |
The following command will rotate the 8 bits of the accumulator one position to the left: |
| A. | True |
| B. | False |
| Answer» B. False | |
| 12. |
This statement will set the address of the bit to 1 (8051 Micro-controller): |
| A. | True |
| B. | False |
| Answer» C. | |
| 13. |
The following program will cause the 8051 to be stuck in a loop: LOOP: MOV A, #00H JNZ LOOP |
| A. | True |
| B. | False |
| Answer» C. | |
| 14. |
This program code will read data from port 0 and write it to port 2, and it will stop looping when bit 3 of port 2 is set: STAT: MOV A, PO MOV P2,A JNB P2.3, STAT |
| A. | True |
| B. | False |
| Answer» B. False | |
| 15. |
This program code will be executed once: STAT: MOV A, #01H JNZ STAT |
| A. | True |
| B. | False |
| Answer» C. | |
| 16. |
This program code will be executed continuously: STAT: MOV A, #01H JNZ STAT |
| A. | True |
| B. | False |
| Answer» B. False | |
| 17. |
The 8259-A is a _________. |
| A. | piority Interrupt Controller |
| B. | priority Resolver |
| C. | interrupt Request Registry |
| D. | control logic |
| Answer» B. priority Resolver | |
| 18. |
______ is used to transfer data between microprocessor and I/O process. |
| A. | 8255A |
| B. | 8279 |
| C. | 8254A |
| D. | 8237A |
| Answer» B. 8279 | |
| 19. |
The symbol, ‘addr 16’ represents the 16-bit address which is used by the instructions to specify the |
| A. | destination address of CALL |
| B. | source address of JUMP |
| C. | destination address of call or jump |
| D. | source address of call or jump |
| Answer» D. source address of call or jump | |
| 20. |
The priority level of interrupt of 8051 for which SI(serial interrupt) interrupt is programmed is |
| A. | level 0 |
| B. | level 1 |
| C. | level 0 or level 1 |
| D. | none of the above |
| Answer» C. level 0 or level 1 | |
| 21. |
The first byte of a short jump instruction represents |
| A. | opcode byte |
| B. | relative address |
| C. | opcode field |
| D. | none of the above |
| Answer» B. relative address | |
| 22. |
Name the read only registers are present in the DS12887? |
| A. | register A, register B |
| B. | register B, register C |
| C. | register C, register D |
| D. | register D, register A |
| Answer» D. register D, register A | |
| 23. |
Which of the following is not an instruction of 8051? |
| A. | arithmetic instructions |
| B. | boolean instructions |
| C. | logical instructions |
| D. | none of the above |
| Answer» E. | |
| 24. |
The logical instruction that affect the carry flag during its execution is |
| A. | XRL A; |
| B. | ANL A; |
| C. | ORL A; |
| D. | RLC A; |
| Answer» E. | |
| 25. |
The conditional control transfer instructions check a bit condition which includes any bit of |
| A. | bit addressable RAM |
| B. | bit addressable SFRs |
| C. | content of accumulator |
| D. | all of the mentioned |
| Answer» E. | |
| 26. |
All conditional jumps are |
| A. | absolute jumps |
| B. | long jumps |
| C. | short jumps |
| D. | none of the above |
| Answer» D. none of the above | |
| 27. |
The RS pin is an input or output for a controller? |
| A. | input |
| B. | output |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» C. both of the mentioned | |
| 28. |
XRL, ORL, ANL commands have |
| A. | accumulator as the destination address and any register, memory or any immediate data as the source address |
| B. | accumulator as the destination address and any immediate data as the source address |
| C. | any register as the destination address and accumulator, memory or any immediate data as the source address |
| D. | any register as the destination address and any immediate data as the source address |
| Answer» B. accumulator as the destination address and any immediate data as the source address | |
| 29. |
JZ, JNZ, DJNZ, JC, JNC instructions monitor the bits of which register ? |
| A. | DPTR |
| B. | B |
| C. | A |
| D. | PSW |
| Answer» E. | |
| 30. |
What is the meaning of the instruction MOV A,05H ? |
| A. | data 05H is stored in the accumulator |
| B. | fifth bit of accumulator is set to one |
| C. | address 05H is stored in the accumulator |
| D. | none of the mentioned |
| Answer» D. none of the mentioned | |
| 31. |
INTR, WR signal are an input/output signal pin ? |
| A. | both are output |
| B. | both are input |
| C. | one is input and the other is output |
| D. | none of the mentioned |
| Answer» D. none of the mentioned | |
| 32. |
8 input DAC has |
| A. | 8 discrete voltage levels |
| B. | 64 discrete voltage levels |
| C. | 124 discrete voltage levels |
| D. | 256 discrete voltage levels |
| Answer» E. | |
| 33. |
In the instruction “MOV TH1,#-3”, what is the value that is being loaded in the TH1 register ? |
| A. | 0xFCH |
| B. | 0xFBH |
| C. | 0xFDH |
| D. | 0xFEH |
| Answer» B. 0xFBH | |
| 34. |
A thermistor is a: |
| A. | sensor |
| B. | adc |
| C. | transducer |
| D. | micro controller |
| Answer» D. micro controller | |
| 35. |
What should be done if we want to double the baud rate? |
| A. | change a bit of the TMOD register |
| B. | change a bit of the PCON register |
| C. | change a bit of the SCON register |
| D. | change a bit of the SBUF register |
| Answer» C. change a bit of the SCON register | |
| 36. |
ANL instruction is used |
| A. | to AND the contents of the two registers |
| B. | to mask the status of the bits |
| C. | all of the mentioned |
| D. | none of the mentioned |
| Answer» D. none of the mentioned | |
| 37. |
PWM allows the control of a DC motor with the same phase, but with different amplitude phases? |
| A. | true |
| B. | false |
| C. | cant be determined |
| D. | none of the mentioned |
| Answer» C. cant be determined | |
| 38. |
Which of the following comes under indexed addressing mode? |
| A. | MOVX A, @DPTR |
| B. | MOVC @A+DPTR,A |
| C. | MOV A,R0 |
| D. | MOV @R0,A |
| Answer» C. MOV A,R0 | |
| 39. |
What is the correct order of priority that is set after a controller gets reset? |
| A. | TxD/RxD > T1 > T0 >EX1 > EX0 |
| B. | TxD/RxD < T1 < T0<EX1 < EX0 |
| C. | EX0 > T0 > EX1 >T1> TxD/RxD |
| D. | EX0 < T0 < EX1 < T1 < TxD/RxD |
| Answer» D. EX0 < T0 < EX1 < T1 < TxD/RxD | |
| 40. |
TF1, TR1, TF0, TR0 bits are of which register? |
| A. | TMOD |
| B. | SCON |
| C. | TCON |
| D. | SMOD |
| Answer» D. SMOD | |
| 41. |
What is the function of SCON register? |
| A. | to control SBUF and SMOD registers |
| B. | to program the start bit, stop bit, and data bits of framing |
| C. | none of the mentioned |
| D. | both of the mentioned |
| Answer» C. none of the mentioned | |
| 42. |
What is the supply that a DS12887 consumes even when the power is switched off? |
| A. | Lithium ion battery |
| B. | Lead battery |
| C. | Both of the mentioned |
| D. | None of the mentioned |
| Answer» B. Lead battery | |
| 43. |
To initialise any port as an output port what value is to be given to it? |
| A. | 0xFF |
| B. | 0x00 |
| C. | 0x01 |
| D. | A port is by default an output port |
| Answer» E. | |
| 44. |
What is the clock source for the timers? |
| A. | some external crystal applied to the micro-controller for executing the timer |
| B. | from the crystal applied to the micro-controller |
| C. | through the software |
| D. | through programming |
| Answer» C. through the software | |
| 45. |
DS12887 is a |
| A. | Timer IC |
| B. | Serial communication IC |
| C. | RTC IC |
| D. | Motor |
| Answer» D. Motor | |
| 46. |
Which instructions have no affect on the flags of PSW? |
| A. | ANL |
| B. | ORL |
| C. | XRL |
| D. | All of the mentioned |
| Answer» E. | |
| 47. |
How can the direction of the DC motor be changed? |
| A. | by changing the torque |
| B. | by changing the switching speed |
| C. | by changing the polarity of voltages connected to the leads |
| D. | by changing the RPM rating |
| Answer» D. by changing the RPM rating | |
| 48. |
Transducers produce output voltage in the form of? |
| A. | an analog voltage in the form of current |
| B. | an analog voltage in the form of voltage |
| C. | an analog voltage in the form of pressure |
| D. | all of the mentioned |
| Answer» E. | |
| 49. |
Which pins of a micro controller are directly connected with 8255? |
| A. | RD |
| B. | WR |
| C. | D0-D7 |
| D. | all of the mentioned |
| Answer» E. | |
| 50. |
Which register is used to make the pulse a level or a edge triggered pulse? |
| A. | TCON |
| B. | IE |
| C. | IPR |
| D. | SCON |
| Answer» B. IE | |