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5. Purpose of registers

As stated on the previous page,

Definition:

A register is a discrete memory location within the CPU designed to hold temporary data and instructions

When a register is being used to move data /instructions from one part of the system to another, this is called a buffer. If you are fetching data from main memory (RAM) that data would pass through a buffer on the CPU before being loaded into another internal register e.g. the instruction register.

In the fetch-decode-exectue cycle (see next mini-website), registers are used extensively to move data and instructions around the CPU. For example, the address of the next instruction is moved from the program counter to the memory address register to initiate a read operation.