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.
| 51. |
Is this a valid statement ? SETB A |
| A. | yes |
| B. | no |
| C. | cant be determined |
| D. | none of the mentioned |
| Answer» C. cant be determined | |
| 52. |
When the call instruction is executed the top most element of stack comes out to be |
| A. | the address where stack pointer starts |
| B. | the address next to the call instruction |
| C. | address of the call instruction |
| D. | next address of the stack pointer |
| Answer» C. address of the call instruction | |
| 53. |
What is the function of the SCLK pin in MAX1112 ? |
| A. | It is used to bring data in |
| B. | It is used to bring data out and send in the control byte, one at a time |
| C. | It is used to get output clock |
| D. | It is used to get serial output |
| Answer» C. It is used to get output clock | |
| 54. |
Find the number of times the following loop will be executedMOV R6,#200BACK:MOV R5,#100HERE:DJNZ R5, HEREDJNZ R6,BACKEND |
| A. | 100 |
| B. | 200 |
| C. | 20000 |
| D. | 20000 |
| Answer» D. 20000 | |
| 55. |
Which bits of the Register A are used for turning on the oscillator? |
| A. | D4 |
| B. | D5 |
| C. | D6 |
| D. | All of the mentioned |
| Answer» E. | |
| 56. |
Which of the following statements are true about DAC0808 ? |
| A. | parallel digital data to analog data conversion |
| B. | it has current as an output |
| C. | both of the mentioned |
| D. | none of the mentioned |
| Answer» B. it has current as an output | |
| 57. |
CJNE instruction makes |
| A. | the pointer to jump if the values of the destination and the source address are equal |
| B. | sets CY=1, if the contents of destination register is greater then that of the source register |
| C. | sets CY=0, if the contents of destination register is smaller then that of the source register |
| D. | none of the mentioned |
| Answer» E. | |
| 58. |
When any interrupt is enabled, then where does the pointer moves immediately after this interrupt has occurred? |
| A. | to the next instruction which is to be executed |
| B. | to the first instruction of ISR |
| C. | to the first location of the memory called the interrupt vector table |
| D. | to the end of the program |
| Answer» D. to the end of the program | |
| 59. |
In unsigned number addition, status of which bit is important? |
| A. | OV |
| B. | CY |
| C. | AC |
| D. | PSW |
| Answer» C. AC | |
| 60. |
What steps have to be followed for interfacing a sensor to a micro controller 8051? |
| A. | make the appropriate connections with the controller, ADC conversion, analyse the results |
| B. | make connections of 8051 with an ADC to convert analog voltage to digital one , send this digital value to the controller, analyse the results |
| C. | interface sensor with the MAX232, send now to micro controller, analyse the results |
| D. | none of the mentioned |
| Answer» C. interface sensor with the MAX232, send now to micro controller, analyse the results | |
| 61. |
DJNZ R0,label is how many bit instruction? |
| A. | 2 |
| B. | 3 |
| C. | 1 |
| D. | Cant be determined |
| Answer» B. 3 | |
| 62. |
Calculate the jump code for again and here if code starts at 0000HMOV R1,#0MOV A,#0MOV R0,#25HAGAIN:ADD A,#0ECHJNC HEREHERE: INC R1DJNZ R0,AGAIN MOV R0,AEND |
| A. | F3,02 |
| B. | F9,01 |
| C. | E9,01 |
| D. | E3,02 |
| Answer» D. E3,02 | |
| 63. |
What is null modem connection? |
| A. | no data transmission |
| B. | no MAX232 |
| C. | the RxD of one is the TxD for the other |
| D. | no serial communication |
| Answer» D. no serial communication | |
| 64. |
Does the two instructions mean the same?1) BACK: DEC R0 JZ BACK2) BACK: DJNZ RO, BACK |
| A. | yes |
| B. | no |
| C. | cant be determined |
| D. | yes and second one is preferred |
| Answer» C. cant be determined | |
| 65. |
8051 series of micro controllers are made by which of the following companies? |
| A. | Atmel |
| B. | Philips |
| C. | None of the mentioned |
| D. | Both of the mentioned |
| Answer» E. | |
| 66. |
On power up, the 8051 uses which RAM locations for register R0- R7 |
| A. | 00-2F |
| B. | 00-07 |
| C. | 00-7F |
| D. | 00-0F |
| Answer» C. 00-7F | |
| 67. |
How many bytes of bit addressable memory is present in 8051 based micro controllers? |
| A. | 8 bytes |
| B. | 32 bytes |
| C. | 16 bytes |
| D. | 128 bytes |
| Answer» D. 128 bytes | |
| 68. |
If we push data onto the stack then the stack pointer |
| A. | increases with every push |
| B. | decreases with every push |
| C. | none of the mentioned |
| D. | both of the mentioned |
| Answer» B. decreases with every push | |
| 69. |
When the micro controller executes some arithmetic operations, then the flag bits of which register are affected? |
| A. | PSW |
| B. | SP |
| C. | DPTR |
| D. | PC |
| Answer» B. SP | |
| 70. |
How is the status of the carry, auxiliary carry and parity flag affected if write instructionMOV A,#9CADD A,#64H |
| A. | CY=0,AC=0,P=0 |
| B. | CY=1,AC=1,P=0 |
| C. | CY=0,AC=1,P=0 |
| D. | CY=1,AC=1,P=1 |
| Answer» C. CY=0,AC=1,P=0 | |
| 71. |
The 8051 is a 40-pin IC. Twenty-two pins are needed for the four I/O ports. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 72. |
The ADC 0804 is an analog-to-digital converter that provides 8-bit output resolution that can be directly interfaced to a microcontroller. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 73. |
Writing counter/loop programs is much more difficult with the introduction of the DJNA and the CJNE instructions. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 74. |
Up to 65K of code memory and 65K of data memory can be added to any of the 8051 family members. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 75. |
The statement LCALL READ passes control to the line labelled READ. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 76. |
The number of data registers is: |
| A. | 8 |
| B. | 16 |
| C. | 32 |
| D. | 64 |
| Answer» D. 64 | |
| 77. |
The special function registers can be referred to by their hex addresses or by their register names. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 78. |
The total amount of external code memory that can be interfaced to the 8051 is: |
| A. | 32K |
| B. | 64K |
| C. | 128K |
| D. | 256K |
| Answer» C. 128K | |
| 79. |
This statement will set the address of the bit to 1 (8051 Micro-controller): SETB 01H |
| A. | 1 |
| B. | |
| Answer» C. | |
| 80. |
Microcontrollers often have: |
| A. | CPUs |
| B. | RAM |
| C. | ROM |
| D. | all of the above |
| Answer» E. | |
| 81. |
Both registers TL0 and TL1 are needed to start Timer 0. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 82. |
Which of the following commands will move the value at port 3 to register 2? |
| A. | MOV P2, R3 |
| B. | MOV R3, P2 |
| C. | MOV 3P, R2 |
| D. | MOV R2, P3 |
| Answer» E. | |
| 83. |
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 | |
| 84. |
The contents of the accumulator after this operation MOV A,#0BH ANL A,#2CH will be |
| A. | 11010111 |
| B. | 11011010 |
| C. | 1000 |
| D. | 101000 |
| Answer» D. 101000 | |
| 85. |
An alternate function of port pin P3.4 in the 8051 is: |
| A. | Timer 0 |
| B. | Timer 1 |
| C. | interrupt 0 |
| D. | interrupt 1 |
| Answer» B. Timer 1 | |
| 86. |
The following command will copy the accumulator to the location whose address is 23H: MOV 23H,A |
| A. | 1 |
| B. | |
| Answer» B. | |
| 87. |
The special function registers are maintained in the next 128 locations after the general-purpose data storage and stack. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 88. |
The start-conversion on the ADC0804 is done by using the: |
| A. | |
| B. | CS line |
| C. | INTR line |
| Answer» B. CS line | |
| 89. |
The total external data memory that can be interfaced to the 8051 is: |
| A. | 32K |
| B. | 64K |
| C. | 128K |
| D. | 256K |
| Answer» C. 128K | |
| 90. |
Which of the following statements will add the accumulator and register 3? |
| A. | ADD @R3, @A |
| B. | ADD @A, R3 |
| C. | ADD R3, A |
| D. | ADD A, R3 |
| Answer» E. | |
| 91. |
Which of the following instructions will move the contents of register 3 to the accumulator? |
| A. | MOV 3R, A |
| B. | MOV R3, A |
| C. | MOV A, R3 |
| D. | MOV A, 3R |
| Answer» D. MOV A, 3R | |
| 92. |
A microcontroller is called a computer on a chip. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 93. |
When the 8051 is reset and the EA 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 | |
| 94. |
The following program will cause the 8051 to be stuck in a loop: LOOP: MOV A, #00H  JNZ LOOP |
| A. | 1 |
| B. | |
| Answer» C. | |
| 95. |
Which of the following commands will copy the contents of location 4H to the accumulator? |
| A. | MOV A, 04H |
| B. | MOV A, L4 |
| C. | MOV L4, A |
| D. | MOV 04H, A |
| Answer» B. MOV A, L4 | |
| 96. |
Device pins XTAL1 and XTAL2 for the 8051 are used for connections to an external oscillator or crystal. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 97. |
The last 96 locations in the internal data memory are reserved for general-purpose data storage and stack. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 98. |
The ADC0804 has ________ resolution. |
| A. | 4-bit |
| B. | 8-bit |
| C. | 16-bit |
| D. | 32-bit |
| Answer» C. 16-bit | |
| 99. |
Different instruction sets must make up for the various members of the 8051 family. |
| A. | 1 |
| B. | |
| C. | 1 |
| D. | |
| Answer» C. 1 | |
| 100. |
The 8051 has ________ parallel I/O ports. |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | 5 |
| Answer» D. 5 | |