| REG# | CE2# | CEl# | A9-A4 | A3 | A2 | A1 | AO | Reg | ster |
| IORD#="L" | IOWR#="L" |
| O | O | O | x | O | O | 0 | x | Data Register(D15-DO) | Data Register(D15-DO) |
| O | 1 | O | x | O | O | 0 | O | Data Register[Even, Odd](D7-DO) | Data Register[Even, Odd](D7-DO) |
| 0 | 1 | 0 | x | 0 | 0 | 0 | 1 | Error Register(D7-DO) | Feature Register(D7-DO) |
| O | 0 | 1 | x | O | 0 | O | x | Error Register(D15-D8) | Feature Register(D15-D8) |
| O | O | O | x | O | O | 1 | 0 | Sector Count Register(D7-DO) Sector Number Register(D15-D8) | Sector Count Register(D7-DO) Sector Number Register(D15-D8) |
| O | 1 | O | x | 0 | O | 1 | 0 | Sector Count Register(D7-DO) | Sector Count Register(D7-DO) |
| O | 1 | O | x | O | O | 1 | 1 | Sector Number Register(D7-DO) | Sector Number Register(D7-DO) |
| O | O | 1 | x | 0 | O | 1 | x | Sector Number Register(D15-D8) | Sector Number Register(D15-D8) |
| 0 | 0 | 0 | x | 0 | 1 | O | 0 | Cylinder Low Register(D7-DO) Cylinder High Register(D15-D8) | Cylinder Low Register(D7-DO) Cylinder High Register(D15-D8) |
| O | 1 | O | x | O | 1 | 0 | 0 | Cylinder Low Register(D7-DO) | Cylinder Low Register(D7-DO) |
| O | 1 | O | x | O | 1 | 0 | 1 | Cylinder High Register(D7-DO) | Cylinder High Register(D7-DO) |
| 0 | O | 1 | x | 0 | 1 | 0 | x | Cylinder High Register(D15-D8) | Cylinder High Register(D15-D8) |
| O | 0 | O | x | O | 1 | 1 | O | Drive Head Register(D7-DO) Status Register(D15-D8) | Drive Head Register(D7-DO) Command Register(D15-D8) |
| 0 | 1 | 0 | x | 0 | 1 | 1 | 0 | Drive Head Register(D7-DO) | Drive Head Register(D7-DO) |
| O | 1 | O | x | 0 | 1 | 1 | 1 | Status Register(D7-DO) | Command Register(D7-DO) |
| O | O | 1 | x | O | 1 | 1 | x | Status Register(D15-D8) | Command Register(D15-D8) |
| O | O | O | x | 1 | O | 0 | x | Data Register(D15-DO) | Data Register(D15-DO) |
| 0 | 1 | 0 | x | 1 | O | O | 0 | Data Register[Even, Odd](D7-DO) | Data Register[Even, Odd](D7-DO) |
| O | 1 | O | x | 1 | O | 0 | 1 | Data Register[Odd](D7-DO) | Data Register[Odd](D7-DO) |
| O | O | 1 | x | 1 | O | 0 | x | Data Register[Odd](D15-D8) | Data Register[Odd](D15-D8) |
| O | O | O | x | 1 | 1 | 0 | 0 | invalid(D7-DO) Error Register(D15-D8) | invalid(D7-DO) Feature Register(D15-D8) |
| O | 1 | O | x | 1 | 1 | O | O | invalid | inval¨id |
| O | 1 | O | x | 1 | 1 | 0 | 1 | Error Register(D7-DO) | Feature Register(D7-DO) |
| O | O | 1 | x | 1 | 1 | 0 | x | Error Register(D15-D8) | Feature Register(D15-D8) |
| 0 | O | 0 | x | 1 | 1 | 1 | O | Alt. Status Register(D7-DO) Drive Address Register(D15-D8) | Device Control Register(D7-DO) invalid |
| O | 1 | O | x | 1 | 1 | 1 | 0 | Alt. Status Register(D7-DO) | Device Control Register(D7-DO) |
| 0 | 1 | 0 | x | 1 | 1 | 1 | 1 | Drive Address Register(D7-DO) | inval¨id |
| O | O | 1 | x | 1 | 1 | 1 | x | Drive Address Register(D15-D8) | invalid |
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