Mouse Input - SUCCESSFULLY REVERSE-ENGINEERED!

I noticed that Nestopia supports a mouse in various Subor and "Educational Computer" ROMs. This got me interested, so I decided to reverse-engineer the mouse protocol. Luckily, it was much simpler than I thought.

The mouse connects to joystick port 2. It then sends these signals, depending on the way it is moved.

• Left-click: A
• Right-click: B
• Move left: Select
• Move right: Select + Start (at the same time)
• Move down: Up (confusing - be careful with this one)
• Move up: Up + Down (at the same time)

Here is some psuedo-code which explains this:

Variables: x, y

Function UpdateCursor

     Read Input Port 2

     If Select and Start are pressed Then

        Increment x

     ElseIf Select is pressed then

        Decrement x

     End If

     If Up and Down are pressed Then

        Decrement y

     ElseIf Up is pressed Then

        Increment y

     End If

     Draw cursor at x, y

End Function

I have not yet had a chance to write any real code which uses this, but it is pretty simple so I should have a basic demo soon.

Also, as I do not have any original hardware (yet), I have relied on Nestopia and FCEU. If anyone has access to original hardware, could they test this?