The following project describes how to construct an AMX compatible PS/2 and USB Mouse adapter for the Amstrad CPC. I’ve never actually owned an [[AMX Mouse|AMX mouse]], in fact I’ve never even seen one other than in pictures. Back in the 80s I had no need for one, but with GUIs like [[FutureOS]] and [[SymbOS]] now available, I decided it was time to get my own… or at least build an equivalent. Like other projects that I’ve shared in the community, I’ve tried to keep this project as simple as possible to construct and as cheap as possible to build, otherwise it scares people from trying to build it for themselves. That said, you will need to be proficient at soldering and possibly need to produce your own PCB, if you wish for want your end product to look like the one above. I have also supplied a single sided layout, to make it easier for those of us who like to produce our own PCBs. While designing the circuit, I realised that most modern mice have a scroll wheel which wasn’t available back then on the AMX. As the CPC has a few inputs spare on the port (Joy2), I decided to make them accessible by binding them to the Joy2 up and down signals. Although this isn’t strictly AMX compatible, I thought the people at [[SymbOS]] or [[FutureOS]], might like to take advantage of them, so consider this adapter is AMX+ compatible. However, due to the joystick ports being split on the CPC Plus series, the scroll wheel feature will only work on standard CPCs unless you create a jumper lead to recombine the two ports again on the Plus.
== Warning / Disclaimer ==
The board presented here measures just 38mm x 60mm and should cause absolutely no stress to the CPCs connector. As well as that, remember that there are connectors left and right of the joystick port that you might want to use simultaneously, the layout here has been designed to keep both the sound socket and tape port free.
A note to beginners: When soldering the parts to the board, always solder the most heat resistant parts first and leave the sensitive ones to last, this avoids destroying a successfully soldered transistor while trying to solder a resistor that’s right beside it. Also, although you may notice that I have soldered the 74LS240 into place, I wouldn’t advise beginners to try this, you will destroy it. Splash out on the extra 4 cents it costs for a suitable socket. If you’re an absolute beginner, there are even sockets available for transistors, but the spacing on this layout probably isn’t correct for them. Also remember that there are wire bridges under each of the ICs! These are really difficult to assemble, if the socket or IC is already soldered into place!
The 9 way Sub-D connector usually has two small bolts protruding left and right of the connector, if you remove these, the metal surround will fall off. I used some superglue to re-attach the metal part. It will work without the metal surround, but this will cause the circuit to bend the CPCs joystick pins over time, so I would recommend you do the same. I also added two M3 screws to hold the Sub-D connector to the PCB, this takes the stress off the pins below the connector, which could otherwise develop cracks in the solder over time as well.
Row9.Bit4 Joy1fire2 LOW when Left mouse button pressed
Row9.Bit6 Joy1fire3 LOW when Middle mouse button pressed
Row6.Bit0 Joy2up LOW when mouse wheel turned towards user (or when "6" pressed on keyboardstandard CPC only) Row6.Bit1 Joy2down LOW when mouse wheel turned towards screen (or when "5" pressed on keyboardstandard CPC only)
== Testing The Mouse ==