A directory of Objective Type Questions covering all the Computer Science subjects. Here you can access and discuss Multiple choice questions and answers for various compitative exams and interviews.

1. 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
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Answer: (d).Both of the mentioned

2. AT89C2051 has RAM of:
a. 128 bytes
b. 256 bytes
c. 64 bytes
d. 512 bytes
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Answer: (b).256 bytes

3. 8051 series has how many 16 bit registers?
a. 2
b. 3
c. 1
d. 0
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Answer: (a).2

4. When 8051 wakes up then 0x00 is loaded to which register?
a. DPTR
b. SP
c. PC
d. PSW
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Answer: (c).PC

5. 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
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Answer: (a).PSW

6. How is the status of the carry, auxiliary carry and parity flag affected if 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
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Answer: (b).CY=1,AC=1,P=0

7. 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
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Answer: (d).PSW.3=0 and PSW.4=1

8. 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
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Answer: (a).increases with every push

9. 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
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Answer: (b).00-07

10. 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
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Answer: (c).16 bytes

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