The Novell and Procomp external SCSI connector is a proprietary variant using a 37-pin D-Sub (DB-37) housing to carry the signals of an 8-bit narrow SCSI-1 bus, rather than the standard Centronics 50-pin or high-density 50-pin connectors defined in ANSI X3.131-1994 (SCSI-2). Like the Apple/Mac DB-25 and Future Domain DB-25 mappings, it remaps the 50-pin SCSI signal set onto a physically incompatible connector — meaning standard SCSI cables cannot be used without an adapter. The interface is single-ended, carries eight data lines (DB0–DB7), one parity bit, nine bus-control signals, and termination power, and is limited to Slow SCSI speeds (up to 5 MB/sec). No independent ANSI or INCITS standard governs this connector; it is a manufacturer-specific implementation that is now entirely obsolete.
37 PIN D-SUB FEMALE at the controller
| Pin | Name | Dir | Description |
|---|---|---|---|
| 1 | GND | - | Ground |
| 2 | GND | - | Ground |
| 3 | GND | - | Ground |
| 4 | GND | - | Ground |
| 5 | GND | - | Ground |
| 6 | GND | - | Ground |
| 7 | GND | - | Ground |
| 8 | GND | - | Ground |
| 9 | GND | - | Ground |
| 10 | GND | - | Ground |
| 11 | GND | - | Ground |
| 12 | GND | - | Ground |
| 13 | GND | - | Ground |
| 14 | GND | - | Ground |
| 15 | GND | - | Ground |
| 16 | GND | - | Ground |
| 17 | GND | - | Ground |
| 18 | GND | - | Ground |
| 19 | TERMPWR | IN/OUT | Termination Power |
| 20 | /DB0 | IN/OUT | Data Bus 0 |
| 21 | /DB1 | IN/OUT | Data Bus 1 |
| 22 | /DB2 | IN/OUT | Data Bus 2 |
| 23 | /DB3 | IN/OUT | Data Bus 3 |
| 24 | /DB4 | IN/OUT | Data Bus 4 |
| 25 | /DB5 | IN/OUT | Data Bus 5 |
| 26 | /DB6 | IN/OUT | Data Bus 6 |
| 27 | /DB7 | IN/OUT | Data Bus 7 |
| 28 | /DBP | IN/OUT | Data Bus Parity |
| 29 | /ATN | IN | Attention |
| 30 | /BSY | IN/OUT | Busy |
| 31 | /ACK | IN | Acknowledge |
| 32 | /RST | IN/OUT | Reset |
| 33 | /MSG | OUT | Message |
| 34 | /SEL | IN/OUT | Select |
| 35 | /C/D | OUT | Control/Data |
| 36 | /REQ | OUT | Request |
| 37 | /I/O | OUT | Input/Output |
Signals
- /DB0–/DB7 — Eight active-low data bus lines forming the 8-bit (narrow) SCSI data path.
- /DBP — Active-low data bus parity line; provides odd parity over DB0–DB7.
- /ATN — Active-low Attention; asserted by the initiator to request a message phase.
- /BSY — Active-low Busy; asserted by any device currently using the bus.
- /ACK — Active-low Acknowledge; handshake response from the initiator during data transfer.
- /RST — Active-low Reset; resets all devices on the SCSI bus.
- /MSG — Active-low Message; driven by the target to indicate a message phase.
- /SEL — Active-low Select; used to select a target or reselect an initiator.
- /C/D — Active-low Control/Data; driven by the target to distinguish command/status (asserted) from data (negated) phases.
- /REQ — Active-low Request; handshake signal driven by the target to request a transfer cycle.
- /I/O — Active-low Input/Output; driven by the target to set data transfer direction relative to the initiator.
- TERMPWR — Termination power supply rail; provides the voltage required by SCSI bus terminators.
- GND — Signal ground; pins 1–18 are all ground, providing shielding between signal pairs.
Notes
- Direction is device-relative to the bus (other devices).
- All signal names are active-low, indicated by the leading slash (e.g. /BSY, /REQ). This follows standard SCSI-1 and SCSI-2 convention (ANSI X3.131-1994).
- This connector is a proprietary remapping of the standard 50-pin narrow SCSI signal set onto a DB-37 housing; it is physically and electrically incompatible with the standard Centronics 50-pin (CN50) and high-density 50-pin (DH50) external connectors.
- The pinout differs from both the Apple/Mac/Amiga DB-25 mapping and the Future Domain DB-25 mapping; none of these proprietary DB connectors are interchangeable.
- Single-ended (SE) signalling only; 5 V logic. Maximum recommended cable length is 6 m at Slow SCSI speeds (up to 5 MB/sec). Active termination is not required at Slow SCSI speeds, but exactly two terminators must be fitted at the two extreme ends of the bus segment.
- No ANSI or INCITS standard defines this connector; it is a manufacturer-specific implementation used by Novell and Procomp host adapters and is entirely obsolete.
- For additional context, see SCSI Technology.