| TRST | <-- | 1 | 8271 FDC |
40 | --- | VCC |
| SELECT Ø | <-- | 2 | 39 | LOW CURRENT | ||
| 4 MHZ CLOCK | --> | 3 | 38 | -- | LOAD HEAD | |
| RESET | --> | 4 | 37 | --> | DIRECTION | |
| READY 1 | --> | 5 | 36 | --> | SEEK/STEP | |
| SELECT 1 | <-- | 6 | 35 | --> | WR ENABLE | |
| !DACK | --> | 7 | 34 | -- | INDEX | |
| DRQ | <-- | 8 | 33 | <-- | WR PROTECT | from drive |
| !RD | --> | 9 | 32 | <-- | READY Ø | |
| !WR | --> | 10 | 31 | <-- | TRACK Ø | |
| INT | <-- | 11 | 30 | <-- | COUNT UP 1 | |
| DØ | <-> | 12 | 29 | --> | WR DATA | |
| D1 | <-> | 13 | 28 | <-- | FAULT | |
| D2 | <-> | 14 | 27 | <-- | RD DATA | Unseparated Data |
| D3 | <-> | 15 | 26 | <-- | DATAW | Data Window |
| D4 | <-> | 16 | 25 | <-- | PLO / SS | |
| D5 | <-> | 17 | 24 | <-- | CS | |
| D6 | <-> | 18 | 23 | -- | INSYNC | |
| D7 | <-> | 19 | 22 | <-- | A1 | |
| GND | --- | 20 | 21 | <-- | A0 |
For full details see the 8271 Intel Floppy Drive Controller data sheet (Zipped TIF)