Microprocessor Mcqs

Q:

The SMOD bit is used to

A) decrease the baud rate by 2 B) increase the baud rate by 4
C) increase the baud rate by 2 D) triple the baud rate
 
Answer & Explanation Answer: C) increase the baud rate by 2

Explanation: The SMOD bit is used to double the baud rate.

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10
Q:

In power down mode,

A) Port pins maintain their logic levels B) SFRs maintain their logic levels
C) Clock signal is disabled D) All of the mentioned
 
Answer & Explanation Answer: D) All of the mentioned

Explanation: In power down mode, the clock signal is disabled and all the port pins and respective SFRs maintain their logic levels.

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10
Q:

The state of signals in power down mode is

A) ALE is high B) PSEN is low
C) ALE and PSEN(active low) are high D) ALE and PSEN(active low) are low
 
Answer & Explanation Answer: D) ALE and PSEN(active low) are low

Explanation: ALE and PSEN(active low) remain low in power down mode of 8051.

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9
Q:

The signal that only pulls the microcontroller(8051) out of the power down mode is

A) CLEAR B) LEAVE
C) RESET D) EXIT
 
Answer & Explanation Answer: C) RESET

Explanation: Only Reset signal can pull 8051 out of the power down mode.

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8
Q:

During power down to save battery, the supply voltage can be reduced to a value of

A) 4 volts B) 2 volts
C) 8 volts D) 1 volt
 
Answer & Explanation Answer: B) 2 volts

Explanation: The supply voltage can be reduced to a value of around 2 volts, during power down to save battery.

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10
Q:

The clock signal is disabled to all parts of 8051 in

A) normal mode B) idle mode
C) power down mode D) addressing mode
 
Answer & Explanation Answer: C) power down mode

Explanation: In power down mode, the clock signal to all parts of 8051 chip is disabled.

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7
Q:

The microcontroller enters into power down mode when

A) SMOD bit of PCON is set B) GF1 bit of PCON is set
C) PD bit of PCON is set D) GF2 bit of PCON is set
 
Answer & Explanation Answer: C) PD bit of PCON is set

Explanation: If the PD bit of PCON register is set, it enters power down mode.

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8
Q:

To come out of idle mode, the external interrupt that is enabled is

A) SI(serial) B) INT0
C) INT1 D) All of the mentioned
 
Answer & Explanation Answer: D) All of the mentioned

Explanation: To come out of idle mode, any external interrupt that is enabled like SI(Serial), INT0 and INT1.

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