IBM Twinax

Twinax cabling is used by the IBM 5250 family of terminals and printers to connect to the System/34, /36, /38, and AS/400 midrange computers ("minicomputers").


  • screw-shell connectors (2 pins + shield, keyed)
  • shielded 110 Ω twisted pair
  • half-duplex balanced transmission
  • 1 Mbit/s transfer-rate
  • up to 7 devices per connection (address 0 – 6; can be non-sequential)
  • termination required, most T-connectors are auto-terminating

Adapter cards:

5250 Emulation Adapter/A
S36/38 Workstation Emulation Adapter
Local Twinax Adapter


Twinaxial' Cabling Troubleshooting Guide (SY31-0703-0)

Using the IBM System 36/38 Emulation Adapter Card As a Time Source (TDB)
Twinaxial Auto-Termination Cable Assembly (TDB)
Improved Surge Supression Circuit for Twinaxial Cable (TDB)

Twinax Connector Pinout

Twinax Cable Adapters (from David Beem)

Many later terminals and terminal cards use DB15 male -or- female connector and the appropriate adapter.

DB25? to Twinax adapter + T connector

DB25 to 2x Twinax attachment cable
for S36/38 Workstation adapter (P/N 72X6263)

DB25 to 2x Twinax attachment cable
for InfoWindow (II?) Terminal

Content created and/or collected by:
Louis F. Ohland, Peter H. Wendt, David L. Beem, William R. Walsh, Tatsuo Sunagawa, Tomáš Slavotínek, Jim Shorney, Tim N. Clarke, Kevin Bowling, and many others.

Ardent Tool of Capitalism is maintained by Tomáš Slavotínek.
Last update: 08 May 2024 - Changelog | About | Legal & Contact