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 provided 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 - MAD Edition! is maintained by Tomáš Slavotínek.
Last update: 05 Dec 2023 - Changelog | Legal Info & Contact