Digital Logic and Microprocessors

Both NAND and NOR gates are considered universal gates because any other logic gate can be implemented using only one type of these gates. Between the options provided, NOR is a universal gate.

To perform an AND operation using NAND gates, you need two: the first NAND gate performs the AND operation (with inputs X and Y), and the second NAND gate acts as an inverter to restore the AND logic.

NAND gates are universal gates, meaning any Boolean expression can be implemented using only NAND gates.

A toggle operation (like an XOR) cannot be performed with a single AND gate because an AND gate is not universal and cannot implement the XOR function on its own.

In a standard SR flip-flop, the state S = 1, R = 1 is considered invalid or forbidden because it leads to an indeterminate state where both outputs Q and Q' attempt to go to 0.

Placing an inverter between the S and R inputs of an SR flip-flop ensures that S and R are always complements of each other. This prevents the forbidden state and creates a D flip-flop, where the output follows the input.

A flip-flop is a bistable multivibrator, which is the fundamental building block of sequential logic circuits, capable of storing exactly one bit of binary information.

To divide a frequency by N, you need n flip-flops such that 2^n >= N. For N = 64, 2^6 = 64, so 6 flip-flops are required.

A multiplexer (MUX) is a combinational circuit that selects one of several input lines and routes it to a single output line based on select signals.

MOV A, #0F5H; A=F5 hex ADDA, #0BH; A=F5+0B=00F5 +0B => 1111 0101 + 0000 1011 = 0000 0000 After the addition register A(destination) contains 00, the flags are as follows: CY = 1 as there is carry out from D7. PF = 1 as the number of 1’s is zero.

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COMPARE is a logical instruction for 8085 microprocessor.

Auxiliary carry (AC) is one of the five status flags of 8085 microprocessor. It stores one if there is a carry from bit 3 to bit 4, counted from right.

This is the correct choice.