Registers and Register Transfer


A register is a group of binary cells. Since cell stores one bit of information. It follows that a register with n cell can store any discrete quantity of information that contains n bits. The state of a register is an n-tuple number of 1's and 0's, with each bit designating the state of one cell in the register.
The content of a register is a function of the interpretation given to the information stored in it. Consider, for example following 16 cell register.

1 1 0 0 0 0 1 1 1 1 0 0 1 0 0 1

Physically one may think of the register is composed of 16 binary cells, with each cell storing either a 1 or a 0. Suppose that the bit configuration stored in the register is as shown. The state of the register is the 16 tuple number.

Register with n cell can be in one of 2n possible states. Now if one assumes that the content of the register represents a binary integer, then obviously the register can store any binary number from 0 to 216 - 1.

Register Transfer

A digital computer is characterized by its registers. The memory unit is known as a collection of thousands of registers for storing digital information. The processor unit is composed of various registers that store operands upon which operations are performed.

The control unit uses registers to keep track of various computer sequences, and every input or output device must have at least one register to store the information transferred to or from the device.