The device contains three general purpose I/O registers; General purpose I/O register 0/1/2 (GPIOR 0/1/2). These registers can be used for storing any information, and they are particularly useful for storing global variables and status flags. General purpose I/O registers within the address range 0x00 - 0x1F are directly bit-accessible using the SBI, CBI, SBIS, and SBIC instructions.