9 General Purpose I/O Registers

The ATtiny3224/3226/3227 devices provide four general purpose I/O registers. These registers can be used for storing any information, and they are particularly useful for storing global variables and interrupt flags. General purpose I/O registers, which reside in the address range 0x1C-0x1F, are directly bit-accessible using the SBI, CBI, SBIS, and SBIC instructions.