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SCSI Connectors

The Small Computer System Interface (SCSI) was introduced circa September 1981 and first became a standard in June 1986, 30 years ago in June 2026!

It evolved in three main versions at least: SCSI-1, SCSI-2, and SCSI-3, which should be backwards compatible with one another: SCSI-3 devices can be used with SCSI-2 controllers, and SCSI-2 and 3 devices can also be used with SCSI-1 controllers. Conversely, lower version devices can be used with higher version controllers. The only limitations would be transfer speed.

In addition to different versions, many different connectors were used to connect SCSI devices, with esoteric names such as "half pitch D-subminiature 68-positions male connector". They are divided into two main categories: parallel and serial, which themselves are divided into internal and external. The table below focuses on parallel external SCSI connectors and tries to make sense of this mess as a help to connect various SCSI devices to various computers

External Parallel SCSI Connectors (images partly from scsikabel.com)

Names

Photos

Versions

Types

Pins

Comments

CN50

SCSI-1

Male

36 (both sides of a row)

Similar to the 36-pin connector used by Centronics for the parallel interface on their printers.

DB25

SCSI-1

Male

25 (2 rows)

Available on many vintage computers, like the Amiga, via the DKB RapidFire Zorro II SCSI-2 controller.

DB50

SCSI-1

Male

50 (3 rows)

Actually, a DD50 connector.

HPDB50

SCSI-1

Male

50 (2 rows)

Half-pitch DB50, also called HDB50 (?) and HDDB50 (high density DB50).

HDI-30

SCSI-1

Male

30 (6 rows)

High Density Interconnect for Apple Macintosh only.

HDCN60

SCSI-1/SCSI-2

Male

60 (both sides of a row)

High-density Centronics.

HPCN50

SCSI-1

Male

50 (both sides of a row)

Half-pitch Centronics.

HD50

SCSI-2

Male

50 (2 rows)

So-called High Density, similar to the HPDB50.

HPDB68

SCSI-2/SCSI-3

Male

68 (2 rows)

Half-pitch DB68 for Wide SCSI-2, also known as SCSI-3, 68-pin version of the HD50.

HDCN68

SCSI-2/SCSI-3

Male

68 (both sides of a row)

High-density Centronics 68 pins.

VHDCI

"SCSI-5"

Male

58 (both sides of a row)

Very High Density Cable Interconnect, also known as an HPCN68 (half-pitch Centronics 68 pins). (SCSI-4 is not a thing...)

Model 611

The Sun Microsystems Model 611 (Product Number 599-2067-01) is an external SCSI drive enclosure made for Ultra-2 Wide SCSI LVD 3.5" hard disks. This gibberish means that the controller in the enclosure supports the Ultra-2 SCSI standard introduced in 1997, provides an HPCN68 female connector, and accepts disks with single-connector attachment (SCA) and low-voltage differential (LVD) signalling. SCA implies that the disks must have only one, centred, male HPCN68 connector, like the Compaq 349536-001 disks. The enclosure itself provides two HPDB68 connectors (in and out), access and termination status LEDs, and SCSI termination.

Sun Microsystems Model 611 External SCSI Drive Enclosure

Photos

Comments

The front of the enclosure itself, with the stylish Sun Microsystems logo.

The back of the enclosure, featuring the On/Off switch, IEC C14 power connector, fan, SCSI logical unit number (LUN) selector, the two HPDB68 connectors, and the termination status LEDs.