pc98_usb: Update reset and LED control command

converter/pc98_usb/README

@@ -147,6 +147,7 @@ Its scan code map is very different from standard types. This is not tested.
 Other PC98 converter projects and resource
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 PC-9800シリーズ テクニカルデータブック HARDWARE 編 1993年 p139, p343
+https://archive.org/stream/PC9800TechnicalDataBookHARDWARE1993/PC-9800TechnicalDataBook_HARDWARE1993#page/n151
 https://archive.org/stream/PC9800TechnicalDataBookHARDWARE1993/PC-9800TechnicalDataBook_HARDWARE1993#page/n355
 
 PC98 to USB
@@ -158,3 +159,25 @@ http://www.tsp.ne.jp/~sawada/mago/src/gka98at.asm
 
 scan code:
 http://ixsvr.dyndns.org/usb2pc98
+
+
+
+NOTES
+-----
+### Tested on
+- PC-9801V
+- DIGITAL WAVE Dboard
+
+
+### RDY
+Current firmware does not control RDY line and it is drived as low to receive data always. While sending command firmware drive the line high.
+
+PC98 host keeps RDY line high to prevent keyboard from sending data while processing.
+
+https://archive.org/stream/PC9800TechnicalDataBookHARDWARE1993/PC-9800TechnicalDataBook_HARDWARE1993#page/n359
+
+### Inhibit key repeating
+The command(9Ch, 70h) works with Raku Raku keybaord but not with Dboard.
+
+### LED indicater
+Dboard has LEDs but it seems to ignore LED control command.