Date   : Sat, 28 Aug 1999 10:27:59 +0100
From   : Stuart Tyrrell <Stuart@...>
Subject: Re: PS2 Mouse

Hi all (copied to the list - I hope it accepts external postings!).


In message <19990826162025.15742.rocketmail@...>
          FARAZ CHOUDHRY <razzledazzler2@...> wrote:

> Hi there, I read about you in the BBC mailing list
> bbc-micro@... and saw your Web page.  A guy called Iain
> Williamson mentioned that you could help out about interfacing some
> modern PC mice to BBC Micros.  I seen your product PS2Mouse+ and is
> that the one?  What kind of mice are the Risc PC ones and can they
> be interfaced to a BBC Micro that way, or in any way?

Iain's since mailed me a little more info, and I think we can do
something here if people want.

As a quick overview, PS2Mouse takes a standard PS/2 mouse and gives
quadrature outputs (costs UKP24.95), PS2Mouse+ (UKP39.95) takes a PS/2
mouse and an Acorn quadrature mouse, and gives quadrature outputs.
Both are currently fitted with Acorn 9 pin mini-DIN connectors.

I'm reasonably sure that we could get these working as if they're an
AMX mouse, so long as we can ascertain pinout. I'm happy to sell them
fitted with IDC connectors at the same price as "normal" if people are
interested.

The only "concern" I have is that if the PS/2 mouse is moved very
quickly, a number of quadrature pulses happen in quick succession -
what happens is thus:

<communication with mouse> <inhibit mouse> <wobble quad lines>
<uninhibit mouse> <repeat>

It could be the case that the AMX software might miss pulses where the
mouse is moved quickly enough that there is more than one unit of
movement within each cycle. Having said that we can easily mess around
with the timings to slow the wobbling of quad lines down enough so
that the beeb can keep track.

So - if people are interested in this the next step is that I borrow a
working AMX mouse from somebody so that I can get the wiring
right (or alternatively if somebody can send me an overview of what
lines do what on the AMX IDC connector). Once we've got that sorted we
can get BBC (AMX compatible) versions ready for sale.

I suppose an alternative is if somebody has an Acorn mouse->AMX
adaptor they've wired up themselves and could let me have the pinout
of that.

Cheers,




Stuart.
-- 
Stuart Tyrrell Developments        Stuart@...                
PO Box 183, OLDHAM. OL2 8FB        http://www.stdevel.demon.co.uk
Tel: 01706 848 600      Orange: 0976 255 256      dFax: 0870 164 1604
** NEW Acorn Trackball UKP34.95    Use PS/2 devices only UKP 24.95 **