Register Transfer

We assign computer registers by capital letters to denote function of the register.

Such as, the register which holds an address for memory unit is usually called a memory address register, represented by MAR. Other examples are as PC (for program counter), IR (for instruction register) and R1 (for processor register).  We show individual flip-flops in an n-bit register by giving numbers to them in sequence from 0 to n - 1, starting from 0 in right most position and increasing the numbers toward left.