MCQ BANK 1 8051 - mcq mic PDF

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“DJNZ R0, label” is ________ byte instruction. a) 2 b) 3 c) 1 d) Can’t be determined Answer: a JZ, JNZ, instructions checked content of _______ register. a) DPTR b) B c) A d) PSW Answer: c When the call instruction is executed the topmost 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: b LCALL instruction takes a) 2 bytes b) 4 bytes c) 3 bytes d) 1 byte Answer: c Are PUSH and POP instructions are a type of CALL instructions? a) yes b) no c) none of the mentioned d) cant be determined Answer: b What is the time taken by one machine cycle if crystal frequency is 20MHz? a) 1.085 micro seconds b) 0.60 micro seconds c) 0.75 micro seconds d) 1 micro seconds Answer: b 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: c Which out of the four ports of 8051 needs a pull-up resistor for using it is as an input or an output port? a) PORT 0 b) PORT 1 c) PORT 2 d) PORT 3

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Which instruction is used to check the status of a single bit? a) MOV A,P0 b) ADD A,#05H c) JNB PO.0, label d) CLR P0.05H Answer: c Which addressing mode is used in pushing or popping any element on or from the stack? a) immediate b) direct c) indirect d) register Answer: b Which operator is the most important while assigning any instruction as register indirect instruction? a) $ b) # c) @ d) & Answer: c Which of the following comes under the indexed addressing mode? a) MOVX A, @DPTR b) MOVC @A+DPTR,A c) MOV A,R0 d) MOV @R0,A Answer: b Is this a valid statement? SETB A a) yes b) no Answer: b Which operations are performed by the bit manipulating instructions of boolean processor? a. Complement bit b. Set bit c. Clear bit d. All of the above ANSWER: (d) Why is CHMOS technology preferred over HMOS technology for designing the devices of MCS-51 family? a. Due to higher noise immunity b. Due to lower power consumption c. Due to higher speed d. All of the above ANSWER: (d) Which characteristic/s of accumulator is /are of greater significance in terms of its functionality? a. Ability to store one of the operands before the execution of an instruction b. Ability to store the result after the execution of an instruction

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c. Both a & b d. None of the above ANSWER: (c) Which general purpose register holds eight bit divisor and store the remainder especially after the execution of division operation? a. A-Register b. B-Register c. Registers R0 through R7 d. All of the above ANSWER: (b) What kind of instructions usually affect the program counter? a. Call & Jump b. Call & Return c. Push & Pop d. Return & Jump ANSWER: (a) What is the maximum capability of addressing the off-chip data memory & off-chip program memory in a data pointer? a. 8K b. 16K c. 32K d. 64K ANSWER: (d) Which mode of timer 2 allow to hold the reload values with an assistance of RCAP2H & RCAP2L register pair? a. 8 bit auto-reload mode b. 16 bit auto reload mode c. 8 bit capture mode d. 16 bit capture mode ANSWER: (b) Where should the pin 19 (XTAL1), acting as an input of inverting amplifier as well as part of an oscillator circuit, be connected under the application of external clock? a. to XTAL2 b. to Vcc c. to GND d. to ALE ANSWER: (c) Which port does not represent quasi-bidirectional nature of I/O ports in accordance to the pin configuration of 8051 microcontroller? a. Port 0 (Pins 32-39) b. Port 1 (Pins 1-8) c. Port 2 (Pins 21-28) d. Port 3 (Pins 10-17) ANSWER: (a) Which memory allow the execution of instructions till the address limit of 0FFFH especially when the External Access (EA) pin is held high? a. Internal Program Memory b. External Program Memory c. Both a & b d. None of the above ANSWER: (a)

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Why are the resonators not preferred for an oscillator circuit of 8051? a. Because they do not avail for 12 MHz higher order frequencies b. Because they are unstable as compared to quartz crystals c. Because cost reduction due to its utility is almost negligible in comparison to total cost of microcontroller board d. All of the above ANSWER: (d) Which signal from CPU has an ability to respond the clocking value of D- flipflop (bit latch) from the internal bus? a. Write-to-Read Signal b. Write-to-Latch Signal c. Read-to-Write Signal d. Read-to-Latch Signal ANSWER: (b) What happens when the pins of port 0 & port 2 are switched to internal ADDR and ADDR / DATA bus respectively while accessing an external memory? a. Ports cannot be used as general-purpose Inputs/Outputs b. Ports start sinking more current than sourcing c. Ports cannot be further used as high impedance input d. All of the above ANSWER: (a) Which address/location in the program memory is supposed to get occupied when CPU jump and execute instantaneously during the occurrence of an interrupt? a. Scalar b. Vector c. Register d. All of the above ANSWER: (b) What kind of triggering configuration of external interrupt intimate the signal to stay low until the generation of subsequent interrupt? a. Edge-Triggering b. Level Triggering c. Both a & b d. None of the above ANSWER: (b) What is the counting rate of a machine cycle in correlation to the oscillator frequency for timers? a. 1 / 10 b. 1 / 12 c. 1 / 15 d. 1 / 20 ANSWER: (b) How many machine cycle/s is/are executed by the counters in 8051 in order to detect ‘1’ to ‘0’ transition at the external pin? a. One b. Two c. Four d. Eight ANSWER: (b) Which among the following control/s the timer1 especially when it is configured as a timer in mode’0′, where gate and TR1 bits are attributed to be ‘1” in TMOD register?

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a. TR1 b. External input at (INT1) c. TF1 d. All of the above ANSWER: (b) What is the maximum delay generated by the 12 MHz clock frequency in accordance to an autoreload mode (Mode 2) operation of the timer? a. 125 μs b. 250 μs c. 256 μs d. 1200 μs ANSWER: (c) Which among the below mentioned sequence of program instructions represent the correct chronological order for the generation of 2kHz square wave frequency? 1. MOV TMOD, 0000 0010 B 2. MOV TL0, # 06H 3. MOV TH0, # 06H 4. SETB TR0 5. CPL p1.0 6. ORG 0000H a. 6, 5, 2, 4, 1, 3 b. 6, 1, 3, 2, 4, 5 c. 6, 5, 4, 3, 2, 1 d. 6, 2, 4, 5, 1, 3 ANSWER: (b) What is the bit transmitting or receiving capability of mode 1 in serial communication? a. 8 bits b. 10 bits c. 11 bits d. 12 bits ANSWER: (b) How is the baud rate determined on the basis of system clock frequency (fsc) in accordance to mode ‘0’ of serial communication? a. (oscillator frequency) / 12 b. [2SMOD / 32] x (oscillator frequency) / [12 x (256 – (TH1)] c. [2SMOD / 64] x (oscillator frequency) d. 2SMOD/ 32 x (Timer 1 overflow rate) ANSWER: (a) Which base-register is preferred for address calculation of a byte that is to be accessed from program memory by base-register plus register-indirect addressing mode? a. DPTR b. PSW c. PCON d. All of the above ANSWER: (a) What does the symbol ‘#’ represent in the instruction MOV A, #55H? a. Direct datatype b. Indirect datatype c. Immediate datatype d. Indexed datatype ANSWER: (c)

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How many bytes are supposed to get occupied while subtracting indirect RAM from an accumulator along with borrow under the execution of SUBB A, @Ri? a. 1 b. 2 c. 3 d. 4 ANSWER:(a) Which rotate instruction/s has an ability to modify CY flag by moving the bit-7 & bit-0 respectively to an accumulator? a. RR & RL b. RLC & RRC c. RR & RRC d. RL & RLC ANSWER: (b) Match the following a. JC rel ——————– 1. Jump if direct bit is set & clear bit b. JNC rel —————— 2. Jump if direct bit is set c. JB bit, rel ————— 3. Jump if direct bit is not set d. JBC bit, rel ———— 4. Jump if carry is set e. JNB bit, rel ————- 5. Jump if carry is not set a. A-3, B-2, C-1, D-4, E-5 b. A-5, B-2, C-4, D-1, E-3 c. A-5, B-4, C-3, D-2, E-1 d. A-4, B-5, C-2, D-1, E-3 ANSWER: (d) Which among the category of program branching instructions allow 16 bit address to be specified & can jump anywhere within 64K block of program memory? a. Long jumps (LJMP) b. Short jumps (SJMP) c. Absolute jumps (AJMP) d. All of the above ANSWER: (a) Match the following instruction mnemonics with their description. a. CJNE A,direct,rel ———— 1. Compare immediate to indirect and Jump if not equal b. CJNE A,#data,rel ———— 2. Compare direct byte to accumulator and Jump if not equal c. CJNE @Ri, #data,rel ——- 3. Compare immediate to register and Jump if not equal d. CJNE Rn, # data rel ——– 4. Compare immediate to accumulator and Jump if not equal a. A-1, B-2, C-3, D-4 b. A-2, B-4, C-1, D-3 c. A-4, B-3, C-2, D-1 d. A-2, B-4, C-3, D-1 ANSWER: (b) How does the microcontroller communicate with the external peripherals/memory? a. via I/O ports b. via register arrays c. via memory d. All of the above ANSWER: (a) Which category of microcontrollers acquire the complete hardware configuration on its chip so as to run the particular application?

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a. Embedded Memory Microcontrollers b. External Memory Microcontrollers c. Both a & b d. None of the above ANSWER: (a) What are the significant designing issues/factors taken into consideration for RISC Processors? a. Simplicity in Instruction Set b. Pipeline Instruction Optimization c. Register Usage Optimization d. All of the above ANSWER: (d) What does the compact and uniform nature of instructions in RISC processors facilitate to? a. Compiler optimization b. Pipelining c. Large memory footprints d. None of the above ANSWER: (b) Which architectural scheme has a provision of two sets for address & data buses between CPU and memory? a. Harvard architecture b. Von-Neumann architecture c. Princeton architecture d. All of the above ANSWER: (a) A valid division instruction always makes: a) CY=0,AC=1 b) CY=1,AC=1 c) CY=0,AC=0 d) no relation with AC and CY Answer: c In 8 bit signed number operations, OV flag is set to 1 if: a) a carry is generated from D7 bit b) a carry is generated from D3 bit c) a carry is generated from D7 or D3 bit d) a carry is generated from D7 or D6 bit Answer: d Which instructions have no effect on the flags of PSW? a) ANL b) ORL c) XRL d) All of the mentioned Answer: d

MCQ ON INTERFACING PART 1

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Which pin of the LCD is used for adjusting its contrast? a) pin no 1 b) pin no 2 c) pin no 3 d) pin no 4 Answer: c For writing commands on an LCD, RS bit is a) set b) reset c) set & reset d) none of the mentioned Answer: b Which command of an LCD is used to shift the entire display to the right? a) 0x1C b) 0x18 c) 0x05 d) 0x07 Answer: a The RS pin is _________ for an LCD. a) input b) output c) input & output d) none of the mentioned Answer: a Which instruction is used to select the first row first column of an LCD? a) 0x08 b) 0x0c c) 0x80 d) 0xc0 Answer: c Which of the following step/s is/are correct to perform reading operation from an LCD? a) low to high pulse at E pin b) R/W pin is set high c) low to high pulse at E pin & R/W pin is set high d) none of the mentioned Answer: c Which of the following step/s is/are correct for sending data to an LCD? a) set the R/W bit b) set the E bit c) set the RS bit d) all of the mentioned Answer: d Which command is used to select the 2 lines and 5*7 matrix of an LCD? a) 0x01 b) 0x06 c) 0x0e d) 0x38 Answer: d Which command of an LCD is used to shift the entire display to the right? a) 0x1C b) 0x18

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c) 0x05 d) 0x07 Answer: a Which control line/s act/s as an initiator by apprising LCD about the inception of data transmission by the microcontroller? a. Enable (EN) b. Register Select (RS) c. Read/Write (RW) d. All of the above ANSWER: a. The display operations in LCD are undertaken on EN line with ______ a. 0 to 1 transitions b. 1 to 0 transitions c. both a & b d. none of the above ANSWER: b. When can a LCD display the text form of data ? a. only when RS line is high b. only when RW line is high c. only when RS line is low d. only when RW line is low ANSWER: a. What is the possible range of current limiting resistor essential for lightening the LED in certain applications after pressing the push-button? a. 25- 55 Ω b. 55-110 Ω c. 110-220 Ω d. 220- 330 Ω ANSWER: d. Which among the below given assertions exhibits the dependency of LED status over them, especially for LED and pushbutton connection? a. Closure of pushbutton b. Low Output pin driven by microcontroller c. Both a & b d. None of the above ANSWER: c. Both a & b What is/are the possible way/s of displaying the data by logic analyzer ? a. Logic state format b. Hexadecimal & Map format c. Timing diagram format d. All of the above ANSWER: d. All of the above Which mandatory contents can be visualized by the hexadecimal display format of a logic analyzer? a. Data Bus b. Address Bus c. Both a & b d. None of the above ANSWER: c. How many samples can be displayed before and after the trigger respectively if the trigger-pulse is delayed by center-trigger mode to display 1024 bit counts? a. 512 & 512 samples respectively b. 512 & 1024 samples respectively

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c. 1024 & 512 samples respectively d. 1024 & 1024 samples respectively ANSWER: d. Why two pins for ground are available in ADC0804? a) for controlling the ADCON0 and ADCON1 register of the controller b) for controlling the analog and the digital pins of the controller c) for both parts of the chip respectively d) for isolate analog and digital signal Answer: d What is the function of the WR pin? a) its active high input used to inform ADC0804 to the end of conversion b) its active low input used to inform ADC0804 to the end of conversion c) its active low input used to inform ADC0804 to the start of conversion d) its active high input used to inform ADC0804 to the start of conversion Answer: c While programming the ADC0808/0809 IC what steps are followed? a) select the analog channel, start the conversion, monitor the conversion, display the digital results b) select the analog channel, activate the ALE signal (L to H pulse), start the conversion, monitor the conversion, read the digital results c) select the analog channel, activate the ALE signal (H to L pulse), start the conversion, monitor the conversion, read the digital results d) select the channel, start the conversion, end the conversion Answer: b What is the difference between ADC0804 and MAX1112? a) ADC0804 has 8 bits and MAX1112 has 1 bit for data output b) ADC0804 is used for adc and dac conversions whereas MAX1112 is used for serial data transmissions c) ADC0804 has 32 bits and MAX1112 has 3 bit for data output d) None of the mentioned Answer: a 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) all of the mentioned d) none of the mentioned Answer: a 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: d INTR, WR signal is 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: c Which factors indicate the necessity of sample and hold circuit in the process of analog-to-digital conversion? a. Instantaneous variation in an input signal b. Analog-to-digital conversion time c. Both a & b d. None of the above

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ANSWER: c. Which errors are more likely to get generated by conversion time and ADC resolution respectively in accordance to the digital signal processing? a. Sampling & Quantization Errors b. Systematic & Random Errors c. Overload & Underload Errors d. None of the above ANSWER: a. What does the RAM location at 44H indicates about the seven segment code? a. 7-segment code for the third character b. 7-segment code for the fourth character c. Display of select code for third display d. Display of select code for fourth display ANSWER: a. It is a characteristic provision of some debuggers to stop the execution after each instruction because__________ a. it facilitates to analyze or vary the contents of memory and register b. it facilitates to move the break point to a later point c. it facilitates to rerun the program d. it facilitates to load the object code program to system memory ANSWER: a. It is feasible for an in-circuit emulator to terminate at the middle of the program execution so as to examine the contents of _________ a. memory b. registers c. both a & b d. none of the above ANSWER: c. Which operations are not feasible to perform by simulator programs in accordance to real time programming? a. Memory Operations b. I/ O Operations c. Register Operations d. Debugging Operations ANSWER: b. Which development tool / program has the potential to allocate the specific addresses so as to load the object code into memory? a. Loader b. Locator c. Library d. Linker ANSWER: b The assembler list file generated by an assembler mainly includes ________ a. binary codes b. assembly language statements c. offset for each instruction d. all of the above ANSWER: d. What kind of address/es is /are usually assigned to program by the linker adopted in an execution of assembler? a. Absolute Address b. Relative Address starting from unity

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c. Relative Addresss starting from zero d. None of the above ANSWER: c What is the principle on which electromagnetic relays operate? a) electromagnetic induction b) motor control c) switching d) none of the mentioned Answer: a What are DPDT relays? a) Single pole, single throw b) Single pole, double throw c) Double pole, double throw d) None of the mentioned Answer: c Why do we need a ULN2803 in driving a relay? a) for switching a motor b) for increasing the current c) for increasing the power d) for switching the voltage Answer: b Why are solid-state relays advantageous over electromechanical relays? a) they need zero voltage circuit b) they need less current to be energised c) they need less voltage to be energised d) none of the mentioned Answer: b How can we control the speed of a stepper motor? a) by controlling its switching rate b) by controlling its torque c) by controlling its wave drive 4 step sequence d) cant be controlled Answer: a The RPM rating given for the DC motor is for? a) no-loaded b) loaded c) none of the mentioned d) all of the mentioned Answer: a How can we change the speed of a DC motor using PWM? a) By changing amplitude of PWM b) By keeping fixed duty cycle c) By changing duty cycle of PWM d) By increasing power of PWM Answer: c 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: c...