FREE BEE Bachelor of Electrical Engineering Digital Logic and Microprocessors Questions and Answers Flashcards

What is the primary function of a multiplexer (MUX) in digital logic?

Answer: Selects one of many inputs and forwards it to a single output

A multiplexer selects one input from multiple sources based on select lines and routes it to a single output.

In the 8085 microprocessor, which register pair is used as the default stack pointer?

Answer: SP register

The 8085 has a dedicated 16-bit Stack Pointer (SP) register that holds the address of the top of the stack.

Which Boolean algebra theorem states that A + A·B = A?

Answer: Absorption theorem

The absorption theorem states that a variable ORed with its AND combination with another variable simplifies to just the original variable.

What is the fan-out specification of a digital logic gate?

Answer: The maximum number of gate inputs that the output can drive

Fan-out specifies the maximum number of same-family gate inputs that an output can reliably drive while maintaining valid logic levels.

Which addressing mode does the 8086 instruction MOV AX, [BX+SI+8] use?

Answer: Based indexed with displacement

This instruction uses the base register BX, index register SI, and an 8-bit displacement, combining all three into based indexed with displacement mode.

What is the purpose of the carry look-ahead technique in adder circuits?

Answer: To reduce propagation delay by computing carry signals in parallel

Carry look-ahead generates all carry bits simultaneously using dedicated logic, eliminating the ripple delay of sequential carry propagation.