Engineering Questions with Answers - Multiple Choice Questions
MCQs on Architecture
1 - Question
8051 microcontrollers are manufactured by which of the following companies?
a) Atmel
b) Philips
c) Intel
d) All of the mentioned
View Answer
Answer: d
Explanation: 8051 microcontrollers are manufactured by Intel, Atmel, Philips/Signetics, Infineon, Dallas Semi/Maxim.
Explanation: 8051 microcontrollers are manufactured by Intel, Atmel, Philips/Signetics, Infineon, Dallas Semi/Maxim.
2 - Question
AT89C2051 has RAM of:
a) 128 bytes
b) 256 bytes
c) 64 bytes
d) 512 bytes
View Answer
Answer: a
Explanation: It has 128 bytes of RAM in it.
3 - Question
8051 series has how many 16 bit registers?
a) 2
b) 3
c) 1
d) 0
View Answer
Answer: a
Explanation: It has two 16 bit registers DPTR and PC.
4 - Question
When 8051 wakes up then 0x00 is loaded to which register?
a) PSW
b) SP
c) PC
d) None of the mentioned
View Answer
Answer: c
Explanation: When 8051 wakes up, Program Counter (PC) loaded with 0000H. Because of this in 8051 first opcode is stored in ROM address at 0000H.
5 - Question
When the microcontroller executes some arithmetic operations, then the flag bits of which register are affected?
a) PSW
b) SP
c) DPTR
d) PC
View Answer
Answer: a
Explanation: It stands for program status word. It consists of carry, auxiliary carry, overflow, parity, register bank select bits etc which are affected during such operations.
6 - Question
How are the status of the carry, auxiliary carry and parity flag affected if the write instruction
MOV A,#9C
ADD 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
View Answer
Answer: b
Explanation: On adding 9C and 64, a carry is generated from D3 and from the D7 bit so CY and AC are set to 1. In the result, the number of 1’s present are even so parity flag is set to zero.
7 - Question
How are the bits of the register PSW affected if we select Bank2 of 8051?
a) PSW.5=0 and PSW.4=1
b) PSW.2=0 and PSW.3=1
c) PSW.3=1 and PSW.4=1
d) PSW.3=0 and PSW.4=1
View Answer
Answer: d
Explanation: Bits of PSW register are CY, AC, F0, RS1, RS0, OV, -, P so for selecting bank2 RS1=1 and RS0=0 which are fourth and third bit of the register respectively.
8 - Question
If we push data onto the stack then the stack pointer
a) increases with every push
b) decreases with every push
c) increases & decreases with every push
d) none of the mentioned
View Answer
Answer: a
Explanation: If we push elements onto the stack then the stack pointer increases with every push of element.
9 - Question
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
View Answer
Answer: b
Explanation: On power up register bank 0 is selected which has memory address from 00H-07H.
10 - Question
How many bytes of bit addressable memory is present in 8051 based microcontrollers?
a) 8 bytes
b) 32 bytes
c) 16 bytes
d) 128 bytes
View Answer
Answer: c
Explanation: 8051 microcontrollers have 16 bytes of bit addressable memory.