The 68000 Microprocessor Many instructions can use the data registers or the address registers in the same way. The data registers are used to store information within the 68000 processor itself. The instruction set supports byte, word and long word addressing. Instruction mnemonics can include suffix of .B, .W. or .L to define data sizes.
Some instructions operate specifically on the address registers.
Byte operations on address registers are NOT permitted. The program counter is 32-bit wide. However, only the lower 24 bits are used by the 68000 in addressing modes. More advanced 680x0 architecture uses the full 32 bits. For some instructions, A7 can be used the same way as any other address register.