Enthusiast reverse engineers world’s smallest HDD to access data with help from an old Nokia N91 and OpenClaw — open source USB bridge unlocks 0.85-inch mechanical Toshiba drive from 2004

Maker Will Whang has developed an open-source MK4001MTD USB Bridge to access data from the world’s smallest mechanical hard drives, Toshiba's 0.85-inch MK4001MTD from 2004. Whang reverse-engineered the drive with the help of an old Nokia N91 and OpenClaw, an open-source USB bridge, to unlock the drive's data. By comparing drives and reader interface pads, Whang built a custom reader based on the USB2240 flash media controller chip, enabling the drive to be accessed as USB mass storage. Despite slow transfer speeds, Whang successfully accessed the drive's data and shared all source code and hardware design files on GitHub.