Bringing USB 3 and USB4/Thunderbolt to Windows 98 to 7

Developer Yeo Kheng Meng released an updated xHCI98 driver that adds USB 3.x and USB4/Thunderbolt support to Windows 98 SE, ME, 2000, XP, Vista and 7, extending an earlier version that drove only the USB 2.0 side of xHCI controllers and capped USB 3.0 flash drives at around 34 MB/s. The source code remains at github.com/yeokm1/xhci98, and Yeo wrote that AI was primarily used to generate the post's diagrams and tables.

In my previous post http://yeokhengmeng.com/2026/08/xhci98-usb-host-driver/ , I introduced xHCI98 , a driver that gives Windows 98 SE, ME, 2000, XP, Vista and 7 working USB on machines whose only USB controller is eXtensible Host Controller Interface xHCI , the only kind most modern machines have. That version had a catch. It only drove the USB 2.0 side of the controller, so even a USB 3.0 flash drive was capped at around 34 MB/s. After that, I decided to go further by giving this driver both USB 3.x and USB4/Thunderbolt support. The latter is so modern that not even all of today’s machines have it. The project source code is still at the same link: https://github.com/yeokm1/xhci98 https://github.com/yeokm1/xhci98 I decided to write this blog post to share my journey on how I managed to add this support in. As with the previous post, most of the words in this blog post are written by me. AI was primarily used to generate the diagrams and tables.