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Weird PS/2 mouse

mit41301mit41301 wrote 12/31/2022 at 18:07 • 2 min read • Like

What is PS/2?

The PS/2 (Personal System/2) port, also referred to as the mouse port or keyboard port, was developed by IBM. It is used to connect a computer mouse or keyboard to an IBM compatible computer. The PS/2 port is a mini DIN plug containing six pins and is still sometimes found on all IBM compatible computers. 

Came across a PS/2 mouse.  

The mouse controller is PIC16C58!

Touch or pressure sensor covered by US5431064A patent 

A pressure sensitive transducer array in which a plurality of transducers are connected in series and in parallel with one another. In one embodiment, a resistive layer is formed from carbon or silver ink on a polyester film. A plurality of conductive shunt elements having greater conductivity than the resistive layer is formed on a second polyester film. The films are placed adjacent to one another with the shunt elements contacting the resistive layer. Voltage is applied across the resistive layer and pressure is applied thereto. As the pressure increases, the number of current paths set up through contact points on the shunt elements increase thereby decreasing the resistance across the resistive layer and increasing current flow. In another embodiment a plurality of plate elements are contained in a plane on one side of a dielectric layer. A plurality of plate elements are contained in a plane on the other side of the dielectric layer. As the layer is pushed together responsive to force applied, total capacitance as measured across the planes of plate elements varies.

Sensor bottom view 

https://patents.google.com/patent/US5431064

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Yann Guidon / YGDES wrote 01/19/2023 at 09:44 point

Nice find !

The PIC16C is not a surprise : in 2002 I developed a PC peripheral that emulated a mouse interface with a PIC over PS/2 miniDIN plugs. It made sense : the OS could get IRQ without effort from the application, and the PS2 protocol could send and receive small commands and status packets.

There was some PS2 protocol emulation code on the 'net back in the days, indeed because someone tried to make their own custom mouse.

Maybe I should resurrect this project and make a proper page on HaD to celebrate the 20 years of this foundational endeavour...

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