Other Ports

Numerous special ports are available, including the following:-

Fibre Channel (FC)

This interface, recognised by ANSI and defined in the SCSI-3 standard, employs Fibre Channel Protocol (FCP) to send data via a fibre-optical cable and coaxial connectors. In the form known as Fibre Channel-Arbitrated Loop (FC-AL) it accommodates up to 126 devices, and is often used for connecting high-speed hard disk drives.


The General-Purpose Instrument Bus (GPIB) is a high-speed parallel interface designed for instrumentation, as defined in the IEEE 488 standard. Although unsupported by most computers, you can control such a bus via a GPIB controller connected to a standard serial port. Also, you may be able to use a special PCI card for a direct GPIB connection.

The interface uses eight multi-purpose bidirectional data lines and a number of control lines wired onto a 24-way connector as shown below:-

1DIO1Data ​Line ​1
2DIO2Data ​Line ​2
3DIO3Data ​Line ​3
4DIO4Data ​Line ​4
5EOIEnd ​Or ​Identify ​(end ​of ​transfer)
6DAVData ​Valid
7NRFDNot ​Ready ​For ​Data
8NDACNot ​Data ​Accepted
9IFCInterface ​Clear ​(initialises)
10SRQService ​Request
13DIO5Data ​Line ​5
14DIO6Data ​Line ​6
15DIO7Data ​Line ​7
16DIO8Data ​Line ​8
17RENRemote ​Enable

Serial Digital Interface (SDI)

This is used for professional digital video hardware, including BetaSP, D-1, D-2, D-3 and D-5 format recorders, as well as associated video cameras. It normally conveys uncompressed 10-bit data via BNC connectors, in high definition (HD-SDI) or standard definition (SD-SDI) form.

Serial Storage Architecture (SSA)

This interface is defined in the SCSI-3 standard. It can use Serial Storage Protocol (SSP) to accommodate up to 127 devices, usually in the form of high-performance hard disk drives. It uses a 4-core screened cable and doesn’t require terminators. The maximum transfer rate is 80 MB/s.


This is really a protocol for controlling mains-powered devices by sending data down mains cables, allowing you to use your computer for home automation. The transmitter module and any number of receiver modules are plugged into the mains wiring. The devices to be controlled are then connected to a receiver module.

Each module is assigned one of 16 ID letters in the range of A to P, whilst each device in a module is assigned one of 16 ID numbers in the range of 1 to 16. Note that modules with the same ID number will switch the connected devices simultaneously. X10 sensors, also with ID codes, can be used to detect changes in light or temperature, for example.

©Ray White 2004.