Registers

• A Register is a fast memory used to accept, store, and transfer data and instructions that are being used immediately by the CPU.
• A Register can also be considered as a group of flip-flops with each flip-flop capable of storing one bit of information.
• A register with n flip-flops is capable of storing binary information of n-bits.
• The flip-flops contain the binary information whereas the gates control the flow of information, i.e. when and how the information?s are transferred into a register.
• Different types of registers are available commercially. A simple register consists of only flip-flops with no external gates.
• The transfer of new data into a register is referred to as loading the register.

• The above figure shows a register constructed with four D-type flip-flops and a common clock pulse-input.
• The clock pulse-input, CP, enables all flip-flops so that the information presently available at the four inputs can be transferred into the four-bit register.