Govt. Exams
Entrance Exams
To represent 15 states, we need n flip-flops such that 2^n ≥ 15. Since 2^4 = 16 ≥ 15, minimum 4 flip-flops are required.
Sequential circuits have memory elements (flip-flops) and their output depends on past inputs. Flip-flops are the basic sequential elements; multiplexers, encoders, and decoders are combinational circuits.
RAM (Random Access Memory) is volatile and loses all data when power is removed. ROM, EPROM, and Flash memory are non-volatile.
A T flip-flop toggles its output when T=1 and holds when T=0, making it ideal for frequency division and counter design.
A demultiplexer with n select lines has 2^n output lines. For 4 select lines: 2^4 = 16 output lines.
A multiplexer with n select lines can handle 2^n input lines. For 3 select lines: 2^3 = 8 input lines.
BCD (Binary Coded Decimal) requires 4 bits to represent decimal digits 0-9 (2^4 = 16 combinations, but only 10 are used).
Asynchronous (ripple) counters work by cascading flip-flops where the output of one flip-flop triggers the next, creating a ripple effect.
Combinational circuits: output = f(present inputs only). Sequential circuits: output depends on present inputs AND past states (memory elements like flip-flops store history)
16×4 RAM means 16 memory words (locations), each storing 4 bits of data. This requires log₂(16)=4 address lines. Total capacity = 16 words × 4 bits = 64 bits
