USB Root Hub
USB allows for a lot of devices to be connected, but they all share the same bandwidth. Some computers will install more than one base port(called the root hub) to allow you to spread your devices across more than one root hub. You can’t tell from how many USB port plugs there are on the computer as each root hub can handle a lot of them. Some systems will have separate root hubs, where one is USB 1.1 only, and the other is USB 1.1/2.0 compatible. The reason is that some 1.1 devices will not work with 1.1/2.0 compatibility, mostly these are very old USB devices. Some systems that have USB ports on the front will have those on a separate root hub
翻译：
USB 根集线器
USB 允许连接许多设备，但它们都共享相同的带宽。有些计算机会安装多个基本端口（称为根集线器），以便您将设备分布在多个根集线器上。 您无法从计算机上有多少个 USB 端口插头来判断，因为每个根集线器都可以处理很多。某些系统将具有单独的根集线器，其中一个仅支持 USB 1.1，另一个与 USB 1.1/2.0 兼容。原因是某些 1.1 设备无法兼容 1.1/2.0，这些设备大多是非常旧的 USB 设备。一些前面有 USB 端口的系统将在单独的根集线器上拥有这些端口
Generic USB Hub
The Generic USB Hub is a HI-SPEED USB device and will function at reduced speed when plugged into a non-HI-SPEED port. HI-SPEED USB Device Plugged into non-HI-SPEED USB Hub. A HI-SPEED USB device is plugged into a non-HI-SPEED USB hub.
翻译：
通用 USB 集线器
通用 USB 集线器是一种 HI-SPEED USB 设备，当插入非 HI-SPEED 端口时会降低速度。 插入非 HI-SPEED USB 集线器的 HI-SPEED USB 设备。HI-SPEED USB 设备插入非 HI-SPEED USB 集线器。
