Keyboard Converting Guide
This is a preview of upcoming Admiral Shark's Keyboards content. This page is considered work-in-progress and should be treated as such.
The Keyboard Converting Guide is designed to help produce a tailored keyboard adapting or converting guide based on your answers to a series of questions asked to identify the keyboard and its connectivity. Please answer each question below with the answers that best apply to your keyboard.
Contents
- Connector: 8-pin modular (8P5C)
- Looks like: RJ-45, ethernet, some serial ports*
- Protocol: IBM PC Mode 2 (Display Station variant)
- Scancodes: IBM scancode set 3
The combination of an 8-pin modular plug typically in an 8P5C configuration, IBM PC Mode 2 protocol and IBM scancode set 3 was used as the primary IBM Display Station (terminal) keyboard interface from 1987 onwards. It may be known as the modular variant of the IBM Display Station serial keyboard interface to contrast it against the earlier DIN plug variant and the plethora of parallel-based terminal keyboard interfaces IBM was using before either variant. "8P5C" refers to the modular connector's size and configuration - 8 maximum pins but just 5 contacts present/utilised.
The use of IBM PC Mode 2 protocol means this interface is related to the AT and Enhanced (PS/2) keyboard interfaces, which all share the same carrier serial format but differ in exact scancode and command set usage. AT variant and Display Station variant keyboards are typically not plug-and-play compatible with each other's hosts without specific software support (which is rare anyway). A Display Station variant keyboard can operate on a PS/2 host provided the operating system and its keyboard driver supports IBM scancode set 3. An Enhanced variant keyboard can be told to switch to set 3, which theoretically makes them compatible with Display Station hosts. But in practice, it is unclear how much this was utilised (if at all) by IBM terminals.
*
Please note that a modular-based IBM Display Station keyboard is not compatible with ethernet and modular-style general serial ports despite using the same physical connector. Adapters for such are also in no way electrically compatible with these keyboards. Trying to use such ports and adapters may damage your keyboard's electronics.
Applicable keyboards
The following IBM and family keyboards are known to use this keyboard interface:
IBM 3151/3152 ASCII Display Station Keyboard
IBM InfoWindow Display Station Enhanced Keyboard
IBM InfoWindow Display Station Quiet Touch Keyboard
IBM InfoWindow Display Station Typewriter Keyboard
Mode 2 terminal to USB always requires active conversion. Since terminal keyboards are not consumer products, traditional stores and online retailers generally do not stock converters for them. Options were even more limited until the 2010s with the advent of Soarer's Converter.
The aforementioned Soarer's Converter or Vial-QMK ibmpc_usb are presently the most common firmware used for converting an IBM Mode 2-based terminal keyboard to USB. The following are currently available pre-made converters that are flashed with either firmware: