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