Detecting disk activity? Help.

I am looking to write a tiny program that can detect when ANY disk activity
takes place. This should be really simple, but I'm having trouble finding
any information on just how to do it.

What is going on here is that I recently purchased a new computer case that
does not have a Disk Activity LED on it, so I never know when the computer
is busy. I've tried several tray apps that do this, but I'm tired of
filling it up with unnecessary cr*p.

I built a tiny box with a low-amp LED on it and plugged into COM1. I can
turn it on/off (with a tiny VB6 app that I wrote) by sending DTR ("Data
Terminal Ready") signals to the modem port. The plan now is to use my tiny
box as a disk activity busy light.

Can anyone point me in the right direction? Thanks.
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-*- Bubba -*-
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