PC98 to USB keyboard protocol converter
=======================================
Target MCU is ATMega32u2 but other USB capable AVR will also work.


Connector
---------
On host/converter:

    8Pin mini DIN
       ___ ___
      /  |_|  \
     / 8  7  6 \
    | 5    4  3 |
     \_ 2   1 _/
       \_____/
     (receptacle)


Wiring: You can change this with editing config.h.

    Pin mini DIN        MCU
    ----------------------------------
    1  ~RST(TXD)        PD3
    2   GND             GND
    3  ~RDY             PD4
    4   RXD             PD2
    5  ~RTY             PD5
    6   NC
    7   NC
    8   5V              VCC




Protocol
--------
Signal: Asynchronous, Positive logic, 19200baud, Least bit first
Frame format: 1-Start bit(Lo), 8-Data bits, Odd-Parity, 1-Stop bit



Build Firmware
--------------
Just use 'make' to bild firmware

    $ make clean
    $ make

To flash firmware

    $ make dfu

then push button on converter to flash firmware.



PC98 Scan Codes
---------------
    ,---. ,---. ,------------------------. ,------------------------. ,------------------------.
    |Pau| |PrS| | F1 | F2 | F3 | F4 | F5 | | F6 | F7 | F8 | F9 | F10| | F11| F12| F13| F14| F15|
    `---' `---' `------------------------' `------------------------' `------------------------'
    ,-------------------------------------------------------------. ,-------.  ,---------------.
    | Esc|  1|  2|  3|  4|  5|  6|  7|  8|  9|  0|  -|  =|JPY|Bspc| |Ins|Del|  |Hom|End|  -|  /|
    |-------------------------------------------------------------| |-------|  |---------------|
    | Tab  |  Q|  W|  E|  R|  T|  Y|  U|  I|  O|  P|  [|  ]|      | |PgD|PgU|  |  7|  8|  9|  *|
    |-------------------------------------------------------`Enter| |-------|  |---------------|
    |Ctl|Cap|  A|  S|  D|  F|  G|  H|  J|  K|  L|  ;|  '|  \|     | |  Up   |  |  4|  5|  6|  +|
    |-------------------------------------------------------------| |-------|  |---------------|
    | Shift   |  Z|  X|  C|  V|  B|  N|  M|  ,|  .|  /| RO| Shift | |Lef|Rig|  |  1|  2|  3|  =|
    `-------------------------------------------------------------' |-------|  |---------------|
     ^3|Kana|Gui|Alt|MHEN|       Space        |HENK|Alt|Gui|App|^2  | Down  |  |  0|  ,|  .| ^1|
       `-------------------------------------------------------'    `-------'  `---------------'
    ^1: Enter on keypad is identical to Enter on alphanumeric portion.
    ^2: Right Alt is ALT on DIGITAL WAVE Dboard while Menu on PC-9821 keyboard.
        App is HOME key on PC98XL keyboard.
    ^3: Caps and Kana are locking keys, either mechanically or by firmware emulation.


    ,---. ,---. ,------------------------. ,------------------------. ,------------------------.
    | 60| | 61| | 62 | 63 | 64 | 65 | 66 | | 67 | 68 | 69 | 6A | 6B | | 52 | 53 | 54 | 55 | 56 |
    `---' `---' `------------------------' `------------------------' `------------------------'
    ,-------------------------------------------------------------. ,-------.  ,---------------.
    | 00 | 01| 02| 03| 04| 05| 06| 07| 08| 09| 0A| 0B| 0C| 0D| 0E | | 38| 39|  | 3E| 3F| 4D| 41|
    |-------------------------------------------------------------| |-------|  |---------------|
    |  0F  | 10| 11| 12| 13| 14| 15| 16| 17| 18| 19| 1A| 1B|      | | 36| 37|  | 42| 43| 44| 45|
    |-------------------------------------------------------`  1C | |-------|  |---------------|
    | 74| 71| 1D| 1E| 1F| 20| 21| 22| 23| 24| 25| 26| 27| 28|     | |   3A  |  | 46| 47| 48| 49|
    |-------------------------------------------------------------| |-------|  |---------------|
    |   70    | 29| 2A| 2B| 2C| 2D| 2E| 2F| 30| 31| 32| 33| 70/7D | | 3B| 3C|  | 4A| 4B| 4C| 4D|
    `-------------------------------------------------------------' |-------|  |---------------|
       | 72 | 77| 73| 51 |        34          | 35 | 79| 78| 5E|    |   3D  |  | 4E| 4F| 50| 1C|
       `-------------------------------------------------------'    `-------'  `---------------'
    5E: HOME on PC98XL keyboard
    79: ALT on DIGITAL WAVE Dboard
    77,78,79: Left Win, right Win and Application on PC-9821 keyboard



PC98 keyboard commands
----------------------
http://www.webtech.co.jp/company/doc/undocumented_mem/io_kb.txt

response from keyboard:
    FAh: ACK
    FCh: NACK

Inhibit repeating key:
    9Ch, 70h

LED control:
    9Dh 7xh

    second byte:
    0111 xxxx
         |||`- NumLock
         ||`-- ?
         |`--- CapsLock
         `---- Kana

Enabling Win and App key on PC-9821 keyboard:
    95h, 03h



Raku Raku keyboard support
--------------------------
NEC PC-9801-98-S02 - raku raku keyboard:
https://deskthority.net/photos-f62/nec-pc-9801-98-s02-t5212.html

To build firmware for the keyboard

    $ make KEYMAP=rakuraku clean
    $ make KEYMAP=rakuraku
    $ make KEYMAP=rakuraku dfu

Its scan code map is very different from standard types. This is not tested.



Other PC98 converter projects and resource
------------------------------------------
PC98 to USB
http://davy.nyacom.net/kbd98usb/

PC98 to PS/2
http://www.tsp.ne.jp/~sawada/mago/c_gka98at.htm
http://www.tsp.ne.jp/~sawada/mago/src/gka98at.asm

scan code:
http://ixsvr.dyndns.org/usb2pc98