Interesting PS/2 vs USB info that I stole from the web
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https://www.eevblog.com/forum/projects/ ... b-touchpad)-reuse-old-laptop-parts-(synaptics-asus-m67n)/
Re: [DIY USB? Touchpad] reuse old laptop parts (Synaptics, Asus M67n)
« Reply #10 on: December 23, 2016, 09:57:10 AM »
Hey, I thought I might contribute my little bit of knowledge here:
Touchpads, and often keyboards, built into laptops are usually PS/2 because that protocol is interrupt-based, meaning that the system does not have to use energy or cpu cycles to poll the devices at the ~1000Hz of usb, insted the system just "listens" for the keyboard/touchpad to tell it that something is happening.
Just another way to cut down on excessive battery usage, to eke out that extra 5 minutes of life.
There are ps/2 to usb converters available which may make the reuse easier, look for "active" ones, they generally work better if the original device was only intended for ps/2 use. Some are available on ebay for ~$2 US if you do a little digging