reverse course

Steven is out of the office for the next few days, so I decided that we must have fun with it. I’ve always thought that software pranks lacked a certain level of sophistication. So, when our mouse flipping software was defeated by the office virus scanning I was overjoyed. This meant that the only course of action was a hardware prank. It turns out that he has a quite old optical mouse, an older Dell unit manufactured by Logitech. This USB mouse uses the Agilent HDNS-2000 chipset. A quick consultation of the circuit board and datasheet revealed that Logitech was using the quadrature output of this device to sense motion. Reversing the quadrature polarity reverses the perceived direction of motion. So, I set about switching XA and XB, YA and YB. After cutting a few pins, and soldering a few jumper wires we were in business. I now have a mouse whose cursor will move down when you move it up, and left when you move it right, and vice-versa. Anyways, thought it was a fun and creative way to torment an employee.