SCSI 1, 2, 3 and 5 connectors

The original SCSI standard was approved in 1986. It supports transfer rates of up to 5 Megabytes per second (MBps) and 7 SCSI devices on an 8-bit bus. The most common connector for SCSI-1 is the Centronics® 50 or Telco 50. A Micro Ribbon 60 connector may also be used.

Approved in 1994, SCSI-2 introduced optional 16- and 32-bit buses called “Wide SCSI.” The transfer rate, normally 10 MBps, can go up to 40 MBps when combined with Fast and Wide SCSI. SCSI-2 usually uses a MicroD 50-pin connector with thumbclips. It’s also known as Mini 50 or Micro DB50. A Micro Ribbon 60 connector may also be used.

Found in many high-end systems, SCSI-3 commonly uses a MicroD 68-pin connector with thumbscrews. It’s also known as Mini 68.
The most common bus width for SCSI-3 is 16-bit with transfer rates at 20 MBps. Serial-bus and fibre-channel protocols are in development.
NOTE: If you’re going from SCSI-3 to SCSI-2, check your equipment to see if it terminates the 16 unused leads. If not, you’ll need a High-Line Terminator.

SCSI-5, a newer type of connector interface, is also called VHDCI (Very High-Density Connector Interface) or a 0.8-mm connector. It’s similar to the SCSI-3 MD68 connector in that it has 68 pins and a much smaller footprint.

SCSI-5 is designed for next-generation SCSI connections where high performance is a key requirement. Manufacturers, such as IBM® and Hewlett-Packard®, are integrating this new 0.8-mm connector design in their controller cards. It’s the connector of choice for advanced SCSI multiport applications, such as Ultra SCSI Fast-20 and the new Low-Voltage Differential Signal (LVDS) technology.
Because of SCSI-5’s special offset cable exit, up to four channels can be accommodated in one card slot. Connections are also easier where space is limited.

Learn more: SCSI Termination