StarLAN

Developed in the mid to late 1980s by AT&T, StarLAN first ran at a speed of 1Mbps. Later, StarLAN10 was created as an enhancement, and ran at 10Mbps.

StarLAN was not originally standardized by any official organizations such as ISO or ITU. It was adopted by other networking vendors such as Hewlett-Packard and Ungermann-Bass.

However, it did provide the basis for the later standard 10BASE-T. With the addition of link beat, a feature to easily detect whether or not a cable was connected, StarLAN10's basic modulation scheme became 10BASE-T.

A major design goal in the StarLAN technologies was compatibility with analog telephone signals in the same cable. The signal modulation was carefully chosen so that it would not affect or be affected by either the analog signal of a normal call or the 20Hz high-voltage analog ring signal.

The TIA-568B wiring pinout standard was chosen, and pair 1 (blue) was left unused to accommodate an analog phone pair. Pairs 2 and 3 (orange and green) carry the StarLAN signals. This greatly simplified the installation of combined voice and data wiring, which was revolutionary in 1990.