A device, accessible to one or more input circuits, that accepts and stores data. Note: A register is usually used only as a device for temporary storage of data. 2. A temporary-memory device used to receive, hold, and transfer data (usually a computer word) to be operated upon by a processing unit. Note: Computers typically contain a variety of registers. General purpose registers may perform many functions, such as holding constants or accumulating arithmetic results. Special purpose registers perform special functions, such as holding the instruction being executed, the address of a storage location, or data being retrieved from or sent to storage.