What are registers and counters in digital systems?

Answer 1

register:- Each flip-flop is a binary cell capable of storing one bit of information. A Register is simply a group of flip-flops. An n-bit register has a group of n flip-flops. The basic function of a register is to hold information within a digital system so as to make it available to the logic elements during the computing process. Since a register consists a finite number of flip-flops and as each of those flip-flops is capable to store a single 0 or 1, there are a finite number of 0-1 combinations that can be stored into a register. Each of those combinations is known as state or content of that register. With flip-flops we can store data bitwise but usually data does not appear as single bits. Instead it is common to store data words of n bit with typical word lengths of 4, 8, 16, 32 or 64 bit. Thus, several flip-flops are combined to form a register to store whole data words. Registers are synchronous circuits thus all flip-flops are controlled by a common clock line. As registers are often use to collect serial data they are also called accumulators.

Counters:- A counter is a sequential circuit that - counts. That means it proceeds through a pre-defined sequence of states where the state of the circuit is determined by the states of all its flip flops. As every state of the circuit can be given a number we can say that a counter produces a sequence of numbers. A commonly used approach is to interpret a circuits state as dual number, so if flip-flop A,B and C are all 0 the counter's state is 0. if A is 1, B is 0 and C is 1 the counter's state is 101 = 5 and so on. The most basic counters will simply increment by 1 with every clock pulse, so after state 100 it will go to 101; the next pulse will let it switch to 110 etc. It is possible to design counters with any needed counting sequence.