http://en.wikipedia.org/wiki/PS/2_connector
No diode. Just different pins used for the mouse clk/data.


peter green wrote:

>>The PS/2 keyboard mouse splitters aren't really anything special. It's
>>really the same pins for each, but one has a diode inside (don't remember
>>which one).
> 
> i thought they used the two spare pins, ofc there may have been two
> different designs (which would explain some splitters not working with some
> laptops)
> 
> 
>>The PS/2 ports aren't meant to be hot-pluggable, so I'm not suprised that
>>you had problems doing that. In my experience, the KEYBOARD can
>>usually be
>>unplugged, and re-plugged without problems, but not the mouse, and never
>>both on a splitter.
> 
> i'm sure i've seen latop manuals say otherwise
> 
> 
>>A friend has an older IBM thinkpad, and he tried a couple of USB-PS/2
>>(mouse and keyboard) converters. One was a cheap no-name, the other was a
>>COMPAQ brand. Neither worked properly UNTIL he tried a different mouse.
>>He was using a microsoft explorer mouse (with more than 3 buttons). Go
>>figure.
> 
> 
> and i found the same issue with a ps/2 cherry keyboard (though i only tried
> one adaptor) whereas with a crappy keyboard i had it worked fine.
> 
> my guess is theese splitters are doing something like powering the device
> off 3.3V or powering it off 5V but using 3.3V signal levels. Either that or
> there is something nasty about how they implement the protocol. Since this
> is the piclist maybe i should try doing a 2550 based converter and see if i
> can get it working well :).
> 
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