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8051 Microcontroller Question & Answers

June 6, 2022 By WatElectronics

This article lists 100 8051 Microcontroller MCQs for engineering students. All the 8051 MC Questions & Answers given below include a hint and a link wherever possible to the relevant topic. This is helpful for users who are preparing for their exams, interviews, or professionals who would like to brush up on the fundamentals of the 8051 Microcontroller.

 8051 has many instructions and functions like 8-bit ALU, timers, and counters which are 16-bit each, the on-chip ram of 128 0r 256 bytes, has an 8-bit data bus, 32-bit address bus, and holds ROM memory size 64kb each.

8051 holds a Harvard architecture, has 16 special function registers, two accumulators A, B, and Program status word has 7 bits where 0-bit is a parity bit and 1st bit is a user-defined bit, 2nd is overflow flag bit, 3rd-4th pins are register select pins, 5th pin is a flag bit holds 0 value.

B-register is used to multiply and divide instructions where 256 bits are addressable. Operands like MOV-which moves the operand, SUB-which subtracts the operand, INC-which increments the operand, DEC-which decrements the operand.

CJNZ, JMP, ORL, ANL, ADDC-which adds the operand with carrying bit, XCH-which exchanges the accumulator values, SUBB-which subtracts and borrows, DJNZ. 8051 is a 40-pin dual inline package that has four ports Port 0, Port 1, Port 2, and Port 3.

1). Mostly ____ bit is an 8051 microcontroller.

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2). 8051 is set up with a ____ pins dual inline combination.

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Read more about 8051 Microcontroller.
3). Read-only memory holds _____ kb of storage in 8051.

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4). Random access memory holds _____ bytes of storage in 8051.

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5). The chip crystal oscillator holds a frequency of ____ MHz in 8051.

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Read more about Crystal Oscillator.
6). How many timers exist in 8051 which is 16-bit?

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7). Pins from _____ are known as Port1 in 8051 Microcontroller.

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8). Pin 9 represents ______ pin in 8051 microcontroller.

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9). Pins from _____ are known as Port3 in 8051 Microcontroller.

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10). Port 3 provides some tasks such as interrupts, timers, and _____ communications.

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11). Pins 18 and 19 combine an ____ crystal to form a structured clock.

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12) Pins from _____ are known as Port2 in 8051 Microcontroller.

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13). Expand PSEN Full form _____?

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14).Expand EA full form ______?

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15).Expand ALE full form ______?

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16).The circuit is powered/supplied by pin____ of 8051 MC.

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17). PSEN explains a wave from the outmost /exterior program _____?

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18). Pins from _____ are known as Port0 in 8051 Microcontroller.

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19). Using port 2, the higher sequence _____ signals are multiplied.

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20). Using port 0, the lower sequence _____ signals are multiplied.

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21). Address latch enable use to distribute data through____ signal of the port.

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22). 8051 has four ___ ports which are of 8-bit each.

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23). ______ are used to connect to input-output ports.

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24). Logic 1 is meant for ____ of power supply.

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25). Logic 0 is meant for ____ of power supply.

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8051 Microcontroller Interview Questions and Answers

 

26). 0V is nothing but connected to _____?

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27). When output pins are arranged at logic 0, then each pin holds a current of ___?

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28). If pins are arranged as inputs, then it provides a ____ current at pull-up resistors.

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29). If every port of 8-bits is active, then the total current is switched to _____?

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30). If every port of 32-bits is active, then the total current is switched to ____.

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31)._______ which alters the program for some time temporary.

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32). How many interrupt signals exist in 8051?

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33).______ register is used to empower and impair interrupts.

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34). For enabling the interrupts _______ register is set to one.

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35). For disabling the interrupts _______ register is set to zero.

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36). IE.5 and IE.6 pin is empty because it is reserved for _____?

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37).To enable/disable _______ interrupt, the ES pin is used.

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38).To enable/disable _____interrupt, the ET1 pin is used.

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39).To enable/disable _____interrupt, the ET0 pin is used.

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40). To enable/disable ______ interrupt1, the EX1 pin is used.

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41). To enable/disable external interrupt0, the ___ pin is used.

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42). Altering the priority levels of interrupts is done using the _____ register.

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43). IP.5 and IP.6 pins which are reserved used for the______?

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44). PS pin represents the priority level of _____ interrupt.

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45). PT0 represents the priority level of _____ interrupt.

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46). PT1 represents the priority level of _____ interrupt.

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47). PX0 represents the 0 priority level of _____ interrupt.

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48). PX1 represents the priority level 1 of _____ interrupt.

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49). Expand PSW full form _______?

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50). Expand SP full form _____?

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8051 Microcontroller MCQs for Exams

51). Memory which is used to add the program is called ______ memory.

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52). Program memory is also known as _____ memory.

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53). Program will be regained when the power is switched off is called _____memory.

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54). For all of the arithmetic operations and logical instructions, _____ is used.

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55). In the B register, R0-R7 are used to store address and data _____?

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56). DPTR is used to operate data in _____ addressing mode.

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57). Data point register holds ____ bit address.

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58). DPL of the data point register holds ____ byte of data.

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59). DPH of the data point register holds a ____ byte of data.

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60). Program counter holds ___ of register?

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61). PSW register is also called as _____ register?

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62). Even though PSW holds an 8-bit register only ____ bits are used?

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63). PSW register holds flags which are called _____ flags?

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64). First bank register starts from one location and stops at the ____H location?

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65). Second bank register starts from the eighth location and stops at the ____H location?

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66). Third bank register starts from the tenth location and stops at the ____ H location?

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67). Final bank register starts from the eighteenth location and stops at the ____ H location?

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68). In 8051, the stack holds ____ bits wide?

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69). Stack holds data from 00 to __ H?

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70). 8051 depends on a ____ architecture?

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71). 8051 uses different methods to access data called ______?

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72). There exist _____ types of addressing modes for microcontrollers?

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73). RI/TI is a _____ interrupt?

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74). In 8051, the on-chip ROM contains _____ of memory?

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75). In 8051, ____ interrupt sources exist?

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8051 Microcontroller Quiz Questions and Answers.

76). Pin 9 in microcontroller _____ is used for resetting and stopping the activity.

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77). Pin 3.1 acts as a ______ pin which is used to transfer the data?

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78). Pin 3.0 acts as a serial pin that is used to ______ the data?

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79). P3.6 is a _____ pin that writes data to the outermost memory?

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80). Pin 40 is a ____ pin for supplying power with 5v?

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81). INC Operand defines the ______ operation?

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82). DEC Operand defines the ______ operation?

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83). ADD Operand defines the ______ operation?

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84). SUB will ______ from the resultant value?

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85). INC and DEC will work as ______ instructions?

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86). MOV operand _____ values from one register to another.

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87). XCH Operand in which exchanging the accumulator and _____ takes place.

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88). SUBB defines, there is no subtraction without _______?

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89). SETB bit in 8051 which _____ the specified bits?

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90). CLR bit in 8051 which _____ the specified bits.

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91). CPL bit in 8051 which _____ the specified bits?

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92). JBC in 8051 defines it as it jumps if the bit is set and ____ the bit?

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93). LJMP and LCALL address instructions are of ____bits?

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94). XRL performs ______ ex-or into accumulator?

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95). ORL operand performs logical ____ operations?

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96). ANL operator performs logical ____ operations?

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97). DJNZ defines _____ the operand and it jumps to the system.

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98). CJNE defines _____the operand and it jumps to the system.

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99). Addition and subtraction bits are instructions which ____ the PSW Flags?

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100). Increment and decrement bits are instructions that don't ____ the PSW Flags?

Hint

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