I saw a mouse! Where? There look, there's loads of 'em!

Ah, mice. The ubiquitous human interaction device that was invented far earlier than you'd expect and which gives us something to throw across the desk when the computer does something stupid (thanks, Windows). 

Not that sort of mouse...

Mice have been mainstream since the late 80's and the Amiga was no different. With its vomit inducing blue GUI in Workbench (pre WB2.0), the Amiga needed a mouse to use any 'serious' software, as well as some games, and they came as standard with the platform. Most Amiga users will fondly remember the squarish 'tank' mouse that Commodore provided with the Amiga and I suspect a large proportion of those users will also remember the joy of replacing it with a third party unit that would be more comfortable and responsive to long sessions of Lemmings.

That's just another actual mouse.

And, would you believe it, in the epic pickup I did recently, I had four Amiga mice included. None had been tested for years and all of them needed a clean having been in storage for so long. So after cleaning up (I'll skip past that) which of them would work? Time to break out Amiga Test Kit.

Four Amiga mice.

Naksha

No x/y movement at all. Buttons register OK

Eklipse

No x movement but y movement OK. Buttons register OK.

Commodore

Working OK

Prism 

Working OK

This is a great start. Two working mice! Interestingly, the Prism mouse has quite a chunky design and the back 1/3 of the case is slightly articulated, so if you put some pressure on the back it moves up and down. Perhaps an early attempt at some proper ergonomics?

But we still have two mice that aren't working. The basic principle of the mechanical mouse is that two disks with small slits are mounted at right angles to each other. Infra-red LEDs and receivers are mounted both sides of the disks and a large ball presses against rollers attached to the disks. As the ball moves, the rollers and disks spin and break the beam between the infra-red LED and its corresponding receiver. The resulting signals are processed by some simple logic in the mouse and the x/y movement is passed back to the Amiga through the mouse/joystick port(s).

One common problem that can prevent the x/y movement from working is if the LEDs or receivers lose 'sight' of the device on the other side of the spinning disk. This is fairly common and, in general, simply bending the LED or receiver (or both) back towards the disk resolves the problem.

Wheel and LEDs

Two wheels at 90 degrees
to each other.

First up, the Eklipse. This mouse has an interesting switch on the bottom that allows for this Amiga version mouse to also do double duty as an Atari ST mouse. I'm not too sure of the differences - I shall have to Google it.  But, as expected, there is a simple two disk arrangement inside for the main x/y control. Since the y movement was OK i.e. up and down, I left that pair of LEDs alone and looked at the others. They didn't seem to be out of alignment as such, but I bent them slightly more towards the disk and did the same for the receivers on the other side. 

And that fixed it! Easy! 

Three down, one to go.

The final mouse was the Naskha mouse. This one also has an Amiga/Atari switch on the bottom. 

Using Amiga Test Kit (ATK) I could see no movement at all from the pointer, but the buttons were working fine. Opening it up, the LEDs/receivers all looked to be perfectly straight. To check that the LEDs were working, I pointed my mobile phones camera at the LEDs to see if I could see the infra-red being emitted. Sure enough, I could see the small purple flashes from the LEDs. So, I tried bending the LEDs towards each other and tried again with ATK. This time, the mouse jittered very slightly in both the x and y axis. This was a very good sign. I tried bending the LEDs and receivers even closer to each other but without fouling the disks. With only a couple of millimetres between the disk and the LED/receiver, the mouse now works perfectly!

What a great result! Four out of four Amiga mice are 100% working! Excellent! 

One each to go with the real critters I had to evict from my workspace. 

Number 3.

Number 4.

For any animal lovers out there, all four living mice were safely transported to a copse a couple of miles away and released. They were all field mice after all.