9 GPR - General Purpose Registers

The AVR64DA28/32/48/64 devices provide four General Purpose Registers. These registers can be used for storing any information, and they are particularly useful for storing global variables and interrupt flags. General Purpose Registers, which reside in the address range 0x1C - 0x1F, are directly bit-accessible using the SBI, CBI, SBIS, and SBIC instructions.