busmouse98-byou

A modified PS/2 or USB to PC-98 quadrature mouse converter.

This firmware is based off of busmouse98 by tyama501. His original version is much more clever than this modified one. Thank you very much for your hard work!

The PS/2 mouse interaction uses the PS2MouseHandler library, which is included. This component is licensed under MIT and was originally developed by Bob Grant.

History

Originally, tyama501 did this busmouse98 firmware, for the Akizuki Denshi AE-ATMEGA328-MINI board. His firmware works well, but it had trouble initializing the optical PS/2 mouse that I bought on Amazon.

This is because the PS/2 mouse contains a USB-and-PS/2 compatible controller chip, the PixArt PAW3515DB, which required additional initialization code to work properly. I ended up merging in the PS2MouseHandler Arduino library to support initialization, and then rewrote some of the original busmouse98 code to not conflict with the use of this library.

Instructions

What You Need

• Arduino Pro Mini, either official or one of the many floating around AliExpress
• FTDI or CH430 USB-to-RS232 adapter
• Edoardo's PS/2 to PC-9801 D-sub adapter PCB, the assembly of which requires:
  • A male DE9 D-sub connector
  • A female PS/2 connector
  • 10kΩ 7-SIP (6 resistors) bussed resistor network
  • Optionally an 0805 SMT LED and a 220Ω 1/4W resistor
• You may need a passive DE9 extension cable. I like the Sega Genesis/MegaDrive ones that are sold on AliExpress, although you should check that all the pins are carried through, and that the male end of the extension cable can fit into the system.

Assembly of Hardware

• Open the ino file in the Arduino IDE.
• Build the ino file, and program this firmware onto the Arduino Pro Mini using an FTDI or CH340 USB-to-RS232 adapter.
• Assemble the mouse adapter according to Edoardo's instructions

Use of Hardware

• Turn PC-98 off.
• Connect the DE-9 connector to the Mouse port of the PC-98.
• Connect the PS/2 mouse to the PS/2 connector of the mouse adapter.
• Use mouse as normal. If it seems twitchy or otherwise defective, alter the timing values in the ino file and reflash it.

Tested With

Mice

• Perixx Perimice 209 3-button PS/2 optical mouse

Computers

• PC-9801RA2

Software

• Artdink's Tokio