IBM
Historically, twinax was the cable specified for the IBM 5250 terminals and printers, used with IBM's midrange hosts, iSeries, (currently Power systems hardware running IBM's 'i' operating system i5/OS), and also with its predecessors, such as the S/32, S/34, S/36, S/38 and AS/400 (Application System 400) minicomputers. The data transmission is half-duplex, balanced transmission, at 1 Mbit/s, on a single shielded, 110 Ω twisted pair.
With Twinax seven devices can be addressed, from workstation address 0 to 6. The devices do not have to be sequential.
Twinax is a bus topology that requires termination to function properly. Most Twinax T-connectors have an automatic termination feature. For use in buildings wired with Category 3 or higher twisted pair there are baluns that convert twinax to twisted pair and hubs that convert from a bus topology to a star topology.
Twinax was designed by IBM as a replacement for RS-232 dumb terminals. Its main advantages were high speed (1 Mbit/s versus 9600 bit/s) and multiple addressable devices per connection. The main disadvantage was the requirement for proprietary Twinax cabling with bulky screw-shell connectors.
Read more about this topic: Twinaxial Cabling, Legacy Applications