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: 5-pin 240° DIN
- Protocol: IBM PC Mode 2 (Display Station variant)
- Scancodes: IBM scancode set 3
The combination of a 5-pin 240° DIN plug, IBM PC Mode 2 protocol and IBM scancode set 3 was used as the primary IBM Display Station (terminal) keyboard interface from 1984 to 1987. It may be known as the DIN variant of the IBM Display Station serial keyboard interface to contrast it against the later modular plug variant and the plethora of parallel-based terminal keyboard interfaces IBM was using before 1984. The plug originally had a screwable metal jacket, but a version with a non-screwable right-angled plastic jacket was later released. The difference only matters when using the keyboard with its original IBM Display Station.
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.
Applicable keyboards
The following IBM and family keyboards are known to use this keyboard interface:
IBM 104-key Model F Converged Keyboard (Type 2)
IBM 122-key Model F Converged Keyboard
IBM 122-key Model M Converged Keyboard (Types 1 and 2)
IBM 316X ASCII Display Station Keyboard
IBM 319X Display Station Enhanced Keyboard
IBM 319X Display Station Quiet Touch Keyboard
- Metal jacket users: IBM 3179, 3180, 3193, 3194, 3205, 3270 PC family and 3290 Model 2
- Plastic jacket users: IBM 3161, 3162, 3163, 3164, 3191, 3192, 3196, 3197 and 3206
DIN plug terminal keyboards from the IBM 3270 family will often have setup switches (a bank of DIP switches) present somewhere on their bottom. A potential use for them is setting a keyboard ID, but some converters that are capable of supporting multiple scancode sets may look for a specific keyboard ID value to determine which set to use.
This being a potential issue is referenced in the Soarer's Converter documentation's "Trouble" page. The default terminal keyboard ID Soarer's Converter looks is the hexadecimal value BFBF, which should be given when all setup switches are set to the "off" (open) position. The documentation recommends checking the setup switches if a terminal keyboard does not operate correctly with it. HID Listen can be used to verify the keyboard ID being returned by the 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:
- ASK Keyboard Archive - P/N 1390123 (1988, IBM-US) [accessed 2024-07-16]. License/note: saved from volatile eBay listing, used under fair dealing.