Govt. Exams
Entrance Exams
JK flip-flop truth table: J=0,K=0 (No change), J=1,K=0 (Set), J=0,K=1 (Reset), J=1,K=1 (Toggle). When both are 1, output toggles.
Full adder has 3 inputs (A, B, Cin) and 2 outputs (Sum, Cout). It differs from half adder which has 2 inputs and 2 outputs.
In BCD, each decimal digit is converted separately to 4-bit binary. 4 = 0100, 7 = 0111. So 47 in BCD = 0100 0111.
For n select lines, 2^n inputs are possible. For 8 inputs: 2^n = 8, so n = 3. An 8:1 multiplexer needs 3 select lines (A, B, C).
Gray code (Reflected Binary Code) is designed such that successive values differ by only one bit. This is useful in error detection and mechanical encoders.
10110.101 = 1×16 + 0×8 + 1×4 + 1×2 + 0×1 + 1×0.5 + 0×0.25 + 1×0.125 = 16 + 4 + 2 + 0.5 + 0.125 = 22.625
AND gate can be implemented using two NAND gates. First NAND gate as AND, second NAND gate as NOT (both inputs same) to negate the output.
NAND gate output is 0 only when all inputs are 1. NAND is NOT of AND operation. For 2-input: output is 0 only when both inputs are 1.
XOR is a derived logic gate made from combination of basic gates (AND, OR, NOT). The three basic gates are AND, OR, and NOT.
