Guide to the 80pin vs. 68pin SCSI Interfaces
This article addresses INTERNAL interfaces only. Please see our articles on external interfaces if you are looking for an external device. There are four internal interface types: 80pin, 68pin, 50pin and 25pin.
We discuss 80-pin and 68-pin here, as they are most relevant today. If your computer was built after 1998 it is highly unlikely that you would need to consider 50pin (used by Narrow/Fast SCSI II devices) or 25pin SCSI (used by SCSI I devices). Please see our other article for details on these interfaces.
The 80pin SCSI interface uses the SCA-2 connector and are ONLY found on hot-swappable SCSI hard drives. There is in fact no 80pin SCSI standard, these are 68pin SCSI devices (16 bit) with 12pins that provide integrated power for hot-swappability (A.K.A. hot-pluggable). 80 pin hot-swappable SCSI hard drives are ONLY used in chassis (usually servers) that have a hot-swap backplane designed for SCSI hard drives with an SCA-2 connector. Good examples of these servers are Dell PowerEdge servers, IBM eServer xSeries servers, Compaq Proliant servers, IBM Netfinity Servers, HP Proliant servers, HP 9000 servers, Sun Enterprise server, Sun Netra servers, etc.You do NOT connect a cable to these drives, they slide into the front of the server case, and clip into place (hence hot-pluggable). This connector is trapezoidally shaped and is 2.25" or 57mm long (longest side of the trapezium) and 0.25" or 6mm wide.
N.B. Servers that use hot-swappable drives, still use 68pin SCSI controllers. The hot-swap backplane has a 68pin connector on it to connect to the controller. The power integration is done by the backplane. Therefore there 80pin controllers, cables or terminators do NOT exist!
The 68pin SCSI interface (16 bit) is the current (1995-2006+) inteface type and is found on ALL current model SCSI controllers, including SCSI RAID controllers. 68pin devices have a separate power connector; usually the standard 4 prong Molex connector found inside computers. Therefore to install a 68pin device you must attach a SCSI cable and a power cable. All current generation , internal SCSI tape drives, internal SCSI CD-ROM drives and internal SCSI DVD-ROM drives use 68 pin SCSI connectors. Most current generation internal SCSI hard drives on desktop computers and workstations use 68pin SCSI hard drives. Good examples of these systems are Dell Precision workstations, Dell Optiplex PCs, Compaq Prosignia PCs, HP workstations, HP AlphaStation workstations, Apple G3 300 minitower, Apple G4 workstations, Apple G5 workstations, some AVID system, SGI Tezro workstations, SGI Fuel workstations & Sun Ultra Workstations. This connector is trapezoidally shaped and is 1.81" or 45mm long (longest side of the trapezium) and 0.2" or 5mm wide.