# xHC Operational Model Overview

DevFeed: [xHC Operational Model Overview](<https://devfeed.tech/articles/xhc-operational-model-overview-33059.md>)

Original publisher: [Read original article](<https://reactos.org/blogs/xhc-operational-model-overview/>)

Published: 2017-06-29T00:00:00Z

Content type: article

Language: en

Sources: [Front Page on ReactOS Website](<https://devfeed.tech/sources/front-page-on-reactos-website.md>)

Topics: [USB](<https://devfeed.tech/topics/usb.md>), [Data structures](<https://devfeed.tech/topics/data-structures.md>), [Development](<https://devfeed.tech/topics/development.md>)

Tags: [development](<https://devfeed.tech/tags/development.md>), [documentation](<https://devfeed.tech/tags/documentation.md>), [free](<https://devfeed.tech/tags/free.md>), [implementation](<https://devfeed.tech/tags/implementation.md>), [linux](<https://devfeed.tech/tags/linux.md>), [mac](<https://devfeed.tech/tags/mac.md>), [open-source](<https://devfeed.tech/tags/open-source.md>), [os](<https://devfeed.tech/tags/os.md>), [react](<https://devfeed.tech/tags/react.md>), [reactos](<https://devfeed.tech/tags/reactos.md>), [usb](<https://devfeed.tech/tags/usb.md>), [win32](<https://devfeed.tech/tags/win32.md>), [winapi](<https://devfeed.tech/tags/winapi.md>)

## AI overview

This progress post explains the xHC operational model and the author's work toward implementing USB control transfers. It describes the hierarchy of rings, transfer descriptors, and transfer request blocks, along with command-ring requirements and plans for USB device initialization.

## Source excerpt

In this post I'm going to give some details on the working of xHC along with my progress. In my opinion Driver development is for the most part thoroughly studying the documentation. I'm working towards my next major target i.e., Implementing Control transfer. In this process I've faced some unforeseen issues. From the previous USB models and the available driver code my estimates of xHC turned out to be inadequate.