Digital Logic and Microprocessors

Accumulator is a 8-bit register that is a part of ALU. This register is used to store 8-bit data and to perform ALU operations. The result is stored in itself.

Rounded rectangles represent functions that transform inputs to outputs.

The turn coordinator displays rate of turn (how fast the aircraft is turning) and also shows the quality of turn (coordinated vs. slipping/skidding). The VSI shows vertical speed, ASI shows airspeed, and neither displays turn rate. The turn coordinator's miniature aircraft indicates both roll rate and yaw rate through the inclinometer ball.

NAND gates are called universal gates because any Boolean function (AND, OR, NOT, etc.) can be implemented using only NAND gates. NOR gates are also universal, but AND, OR, and NOT gates individually cannot implement all Boolean functions by themselves.

A half adder is a digital circuit that adds two binary digits (bits) and produces a sum and carry output. It operates on only 2 bits at a time, unlike a full adder which handles three inputs including carry-in.

Or gate is true when either or both inputs are true, otherwise it is false.

In sequential circuits (like flip-flops, counters), the output depends on both the present inputs and the present state (which stores past inputs). This memory of past states is what makes it 'sequential'. Combinational circuits depend only on present inputs.

Master-slave JK flip flop is specifically designed to eliminate the race-around condition by using two flip flops in a master-slave configuration. The master responds during the positive clock edge while the slave responds during the negative edge, preventing the output from changing multiple times during a single clock pulse.

Correct Answer: 3 2ⁿ = MOD, Since we require to count till 5 (101), so 3 flip flops are required.

JK flip flop can function as a T flip flop when both J and K inputs are connected together (J=K). When J=K=0, the flip flop maintains its state (Q stays same). When J=K=1, it toggles (Q changes), which is exactly the behavior of a T flip flop where T=0 holds and T=1 toggles.

A mod-10 counter requires 4 flip flops because the number of states is 10 (0 to 9). With n flip flops, we can represent 2^n states. For 2^3=8 < 10 < 2^4=16, we need 4 flip flops to accommodate 10 states, though 6 states will be unused.

Excitation table specifies the input conditions required for a flip flop to transition from its present state to the next state. Unlike a truth table that shows output for given inputs, an excitation table shows what inputs are needed to achieve desired state transitions.

A 4-bit down counter counts downward. When it reaches 0000 (the minimum value) and another clock pulse arrives, it wraps around to the maximum value 1111 (15 in decimal). This is the underflow behavior of down counters.

A four-variable logic expression has 2^4 = 16 possible combinations (minterms). A 16:1 multiplexer can realize any 4-variable function by connecting each minterm to the corresponding input line and using the 4 variables as select lines.