IBM 4704 to USB keyboard converter

This firmware converts IBM 4704 keyboard protocol to USB HID.

Keyboard initialization process takes a few seconds at start up. During that you will hear buzzer from the keyboard. You need to plug USB cable after hooking up your keyboard to the converter.

Keyboard models

IBM capacitive switch models:

6019273 Model 100 50-key (grid layout)      http://kishy.dyndns.org/?p=977
6019284 Model 200 62-key Alpha(60% layout)  http://kishy.dyndns.org/?p=894
6019303 Model 300 77-key Expanded Alpha     http://kbtalking.cool3c.com/article/23272
6020218 Model 400 107-key Full key          http://kishy.dyndns.org/?p=980

Alps switch(vintage Green) models:

5954339 Japanese 102-key    http://deskthority.net/post87127.html#p87127
6112883 Japanese 102-key    http://geekhack.org/index.php?topic=52888.msg1194489#msg1194489
6112884 Japanese 102-key    http://geekhack.org/index.php?topic=50437.msg1193047#msg1193047
6341739 Chinese 102-key     http://geekhack.org/index.php?topic=52888.msg1176566#msg1176566

Connector

Keyboard Plug from front:

DSUB-9
-------------
\ N 2 3 4 5 /
 \ N N N N /
  ---------
2   GND
3   VCC 5V
4   DATA
5   CLOCK
N   No connection/No pin.

Connection

In case of using ATMega32U4(Teensy2.0):

1. Supply power with VCC and GND.
2. Connect CLOCK to PD1 and DATA to PD0. You can change pin with config.h.
3. Optionally you may need pull-up register. 1KOhm probably work.

Build Firmware

Just run make:

$ make

To select keymap:

$ make KEYMAP=[plain|...]

Keymap

Several version of keymap are available in advance but you are recommended to define your favorite layout yourself. To define your own keymap create file named keymap_<name>.c and see keymap document(you can find in top README.md) and existent keymap files.