> Stephen D. Barnes wrote:
> > Does anyone know where I can find a schematic diagram for the
> > standard two button PS/2 style MS mouse?
> > Google does not give me any hope.

Mike Singer wrote:
> Perhaps the specs of
>
> EM84502 PS/2 MOUSE CONTROLLER
>
> will give you some hope.
>
> Mike.

Sure did!
I am aware that most mice, PS/2 or standard serial, use the same general encoder scheme.
The Microsoft mouse that I might use has small switching transistors in the positive
supply line to the IR emitters. It appears that the emitters are not active until the
mouse receives initialization from the PS/2 port. Interesting to note is that I have
another Microsoft mouse of the same model and version number that does not use the
transistors or the PIC16C58, but instead has a Zilog Z86C17 and uses three pins tied
together (for current handling apparently) to switch the emitters. None of the PS/2 mouse
schematics I have seen since beginning my search yesterday have depicted this method of
encoder interfacing. What would be the purpose of disabling the emitters? Mouse security?
:o)

Regards,
Stephen D. Barnes

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