Pin 1: Ground
Pin 18: Direction
Pin 2: *Change
Pin 19: Ground
Pin 3: Unused
Pin 20: *Step
Pin 4: *In Use 1
Pin 21: Ground
Pin 5: Ground
Pin 22: *DKWD
Pin 6: *In Use 0
Pin 23: Ground
Pin 7: Ground
Pin 24: DKWE (Write Enable?)
Pin 8: *Index
Pin 25: Ground
Pin 9: Ground
Pin 26: *TRKD
Pin 10: *Select 0
Pin 27: Ground
Pin 11: Ground
Pin 28: *Write Protect
Pin 12: *Select 1
Pin 29: Ground
Pin 13: Ground
Pin 30: *DKRD
Pin 14: Unused
Pin 31: Ground
Pin 15: Ground
Pin 32: *Side
Pin 16: *MTRI
Pin 33: Ground
Pin 17: Ground
Pin 34: *Ready
Note: some 3.5-inch drives may use different pins for the *Change (diskchange) signal.