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


Connector
---------

    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'

    $ cd pc98_usb
    $ make

Then, load the binary to MCU with your favorite programmer.



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

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



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:
    0x9C, 0x70

LED control:
    9Dh 7xh

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