Short for Programmed Input/Output, a method of transferring data between two devices that uses the computer’s main processor as part of the data path. ATA uses PIO and defines the speed of the data transfer in terms of the PIO mode implemented, as shown below:
| PIO Mode | Data Transfer Rate (MBps) | Standard |
| 0 | 3.3 | ATA |
| 1 | 5.2 | ATA |
| 2 | 8.3 | ATA |
| 3 | 11.1 | ATA-2 |
| 4 | 16.6 | ATA-2 |