Apple IMAC User Manual - Page 39
New Technologies - 23, always the case.
UPC - 067540444435
View all Apple IMAC manuals
Add to My Manuals
Save this manual to your list of manuals |
Page 39 highlights
Basics New Technologies - 2 3 • Hubs, which serve as connection points for devices. Hubs also provide device detection, speed matching, and power control. Hubs connect to the host using the 12 Mbps connection speed. Hubs may be "bus-powered" by the USB, or be "self-powered" by an external power source (like an AC adapter). Only hubs can connect to the host. Hubs can also connect to other hubs, providing expansion to the 127 device limit (see the example tree diagram below). Hubs can be freestanding, or embedded in other items (displays, keyboards, etc.). Most freestanding external hubs provide 4 Type A ports, but this is not a always the case. Note: When troubleshooting power errors that buspowered hubs can't be connected to bus-powered hubs, since not enough power is provided to power the device ports. Instead, to extend the USB properly, users should alternate self-powered and bus-powered hubs.