This set of IOT Multiple Choice Questions & Answers (MCQs) focuses on “Microcontroller (8051)”.
1. What do you mean by micro in microcontroller?
a) Distance between 2 IC’s
b) Distance between 2 transistors
c) Size of a controller
d) Distance between 2 pins
Explanation: Micro means 10-6 which gives the distance between 2 element transistors which is called as Micron Technology.
2. What is the bit size of the 8051 microcontroller?
Explanation: It is an 8-bit microcontroller which means most of the operations are limited to 8 bit only.
3. Name the architecture and the instruction set for microcontroller?
a) Van- Neumann Architecture with CISC Instruction Set
b) Harvard Architecture with CISC Instruction Set
c) Van- Neumann Architecture with RISC Instruction Set
d) Harvard Architecture with RISC Instruction Set
Explanation: Harvard architecture has different memory spaces for both program memory and data memory with Complex Instruction Set Computer(CISC).The difference between CISC and RISC is RISC has few instructions than CISC. Where as in Van- Neumann, program and data memory are same. Van- Neumann is also called as Princeton architecture.
4. Number of I/O ports in the 8051 microcontroller?
a) 3 ports
b) 4 ports
c) 5 ports
d) 4 ports with last port having 5 pins
Explanation: It has 4 ports with port0 act as I/O port and also multiplexing of address and data bus. Port1act as I/O port. Port 2 act as I/O and also like address lines. Port 3 act as I/O and also for external peripherals.
5. Is ROM is used for storing data storage?
Explanation: RAM is used for storing data storage and ROM is used for storing program memory.
6. SCON in serial port is used for which operation?
a) Transferring data
b) Receiving data
d) Controlling and transferring
Explanation: There are 2 pins available in serial port. One is used for transmission and other is used for receiving data. SCON is the bit in the serial port which is used for controlling the operation.
7. Program counter stores what?
a) Address of before instruction
b) Address of the next instruction
c) Data of the before execution to be executed
d) Data of the execution instruction
Explanation: Points to the address of the next instruction to be executed from ROM .It is 16 bit register means the 8051 can access program address from 0000H to FFFFH. Total 64KB of code.
8. Auxiliary carry is set during which condition?
a) When carry is generated from D3 to D4
b) When carry is generated from D7
c) When carry is generated from both D3 to D4 and D7
d) When carry is generated at either D3 to D4 or D7
Explanation: When carry is generated from D3 to D4, it is set to 1, it is used in BCD arithmetic.
9. What is order of the assembly and running 8051 program?
Explanation: After writing the program in editor and compilation first .asm, .lst, .obj, .hex are created.
10. The use of Address Latch Enable is to multiplex address and data memory.
Explanation: That is used for multiplexting address and data ie., the same line carries address and data. To indicate when it carries address, ALE is emitted by 8051.
11. Which pin provides a reset option in 8051?
a) Pin 1
b) Pin 8
c) Pin 11
d) Pin 9
Explanation: Reset pin is utilized to set the micro controller 8051 to its primary values, whereas the micro controller is functioning or at the early beginning of application. The reset pin has to be set elevated for two machine rotations.
12. External Access is used to permit ____________
b) Power supply
d) Memory interfacing
Explanation: External Access input is employed to permit or prohibit outer memory interfacing. If there is no outer memory needed,this pin is dragged by linking it to Vcc.
13. What is the address range of SFRs?
a) 80h to feh
b) 00h to ffh
c) 80h to ffh
d) 70h to 80h
Explanation: In 8051 there certain registers which uses the RAM addresses from80h to ffh. These are called as Special Function Registers. Some of the SRFrs are I/o ports and control operations as TCON, SCON, PCON.
14. How many interrupts are there in micro controller?
Explanation: An interrupt is the external or internal event that disturbs the microcontroller to inform if that needs its services. There are 5 interrupts :
Timer 0 overflow interrupt
Timer 1 overflow interrupt
External Interrupt 0
External Interrupt 1
Serial port events.
15. Timer 0 is a ________ bit register.
Explanation: The Timer 0 is a 16-bit register and can be treated as two 8-bit registers and these can be accessed similar to any other registers.
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