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Mousing It

By Peter Naulls. Published: 17th Mar 2005, 13:49:05 | Permalink | Printable

Ian Nichols shows the DIY mouse way

Optical quadrature mouseIn a recent usenet posting in reply to a query about where to obtain Acorn Mice, Ian Nichols commented that he'd had success modifying standard optical PS/2 mice for use on RiscPCs.

As you may know, Acorn machines from the Archimedes up to the RiscPC have an atypical mouse interface, normally referred to as "quadrature". Outside of Acorn machines, these were also widely used on Sun machines and terminals. Historically, most mice on other platforms were serial, and later PS/2 and more recently, USB. Many mice now available for purchase work on both PS/2 and USB interfaces. PS/2 is also used for the keyboard interface on RiscPCs.

Even at the time of the RiscPC manufacture, the quadrature interface was unfashionable, and the story goes that Acorn only stuck with it because of supplies of components. They later ditched this, and A7000s and A7000+s received a PS/2 interface, as was the norm on PCs at the time.

Still, this left existing users who required a new mouse a relatively expensive replacement option from Acorn. To the rescue came STD, who created a PS/2 adaptor allowing attachment of the growing range of PS/2 mousing options from the likes of Logitech. Later, STD produced a smaller and cheaper option, the PS2MouseMini, a small cable adapter performing much the same job. Soon after, Castle produced a similar product. Both STD and Castle also produced their own Acorn-compatible mice.

DIYing it
In November 2003, Ian Nichols tells his readers, he discovered that some optical mice (those are the ones without wheels, but use LED reflections to determine motion) contain chips that are able to output quadrature signals as well as the PS/2 signalling. Screwdriver and soldering iron in hand, and using a cable from an Acorn mouse, Ian went onto to modify several mice for himself and fellow club members.

If you fancy having a go yourself, and saving a few pennies, then Ian has recently documented the whole thing, on his website.


Ian's original post
Castle Technology Optical mouse conversion plans

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Would there be a problem with Ian's site as it appears to be not working?

 is a RISC OS Userem2ac on 17/3/05 2:44PM
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[link] works

 is a RISC OS Usermavhc on 17/3/05 2:45PM
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Beware, read the Usenet thread before buying mice. It only works with certain models of optical mice.

 is a RISC OS Usercaliston2 on 17/3/05 4:41PM
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Also [link] is in the standard google groups format, not the new crap one that also doesn't work as well on RISC OS browsers

 is a RISC OS Usermavhc on 17/3/05 11:57PM
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If your serial port is free, you can save a lot more pennies by buying a cheap serial mouse. I got a nice 3 button serial mouse from MAPLIN for 2.58

 is a RISC OS UserIvanDobski on 21/3/05 5:14PM
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As a spoiler before I buy my own first RISC OS computer, would somebody care to point out where the SELECT, MENU and ADJUST buttons are on the mouse pictured?

While I've seen similar (scrollwheel) mice with a third button on the side - I expect I'll be missing the traditional 3-buttons on top arrangement for some time.

 is a RISC OS Usercdaniels on 25/3/05 2:24PM
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Select is the left hand mouse button. Menu is the middle mouse button, and on scroll wheel mice, the wheel when pressed down acts as a button. Adjust is the right hand mouse button.

I use a 3 button scroll wheel mouse (the wheel acts as the middle button) with my RiscPC and it's great.

 is a RISC OS Userdiomus on 25/3/05 2:37PM
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Is it easy to push the scrollwheel button without causing any scrolling?

 is a RISC OS Usercdaniels on 25/3/05 4:10PM
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Yes, I find that it is. You can push down without scroling.

 is a RISC OS Userdiomus on 25/3/05 5:17PM
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