When addressing I/O Registers as data space using LD and ST instructions, the provided offset must be used. When using the I/O specific commands IN and OUT, the offset is reduced by 0x20, resulting in an I/O address offset within 0x00 - 0x3F.
| Bit7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| DDRD7 | DDRD6 | DDRD5 | DDRD4 | DDRD3 | DDRD2 | DDRD1 | DDRD0 |
| AccessR/W | R/W | R/W | R/W | R/W | R/W | R/W | R/W |
| Reset0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
Port D Data Direction [n = 7:0]