20 PIN UNKNOWN CONNECTOR
| Pin | Name | Description | 
|---|---|---|
| 1 | GND | Ground | 
| 2 | PH0 | Phase 0: state control line | 
| 3 | GND | Ground | 
| 4 | PH1 | Phase 1: state control line | 
| 5 | GND | Ground | 
| 6 | PH2 | Phase 2: state control line | 
| 7 | GND | Ground | 
| 8 | PH3 | Phase 3: register write strobe | 
| 9 | +5V | +5 volts | 
| 10 | /WRREQ | Write data request | 
| 11 | +5V | +5 volts | 
| 12 | SEL | Head select | 
| 13 | +12V | +12 volts | 
| 14 | /ENBL | Drive enable | 
| 15 | +12V | +12 volts | 
| 16 | RD | Read data | 
| 17 | +12V | +12 volts | 
| 18 | WR | Write data | 
| 19 | +12V | +12 volts | 
| 20 | n.c. | Not connected | 
Contributor: Joakim Ögren
  Source:
  Apple Power Macintosh 5400 Developer Note
  Copyright © The Hardware Book Team 1996-2001.
  May be copied and redistributed, partially or in whole, as appropriate.
 Document last modified: 2000-07-07