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USB 1.1: FAQ (1 of 4)

  • Last Modified: February 15, 2006
  • Article: TA24945
  • Old Article: 30650
This article has been archived and is no longer updated by Apple.
This article contains frequently asked questions (FAQ) regarding USB, with answers to those questions. Additional articles are listed at the bottom of this article.

Products Affected

Power Mac, iMac, PowerBook G3

Questions answered in this article:
  1. What is USB 1.1?
  2. How fast is USB 1.1 compared to other connection methods?
  3. What is a USB hub?

Question 1: What is USB 1.1?

Answer: Universal Serial Bus (or USB for short) is an industry standard for connecting peripheral devices to personal computers. Apple is adopting USB in its products for a variety of reasons:

  • it's an industry standard, so there will be a wide variety of solutions available to Apple customers
  • it offers the true plug-and-play simplicity our customers expect from Apple products
  • it's fast, offering data transfer rates of up to 12Mbps
  • it can support up to 127 devices!
  • it features hot plug and hot unplug--that is, you don't have to shut down iMac to connect a new or disconnect an existing USB device
As well as USB 1.1, as described above, USB 2.0 is a newer industry standard that allows for data transfer rates of up to 480Mbps. The data in this article is for USB 1.1.

Question 2: How Fast is USB 1.1 Compared to Other Connection Methods?

Answer: USB offers data transfer rates of up to 12Mbps. This compares very favorably to other Apple connection methods:

Connection Method
Data Transfer Rate
Used For
ADB.01Mbps Input devices like mice, keyboards, joysticks, etc.
Serial.023Mbps--2Mbps QuickDraw printers and telephony devices
USB12Mbps All of the above, and more
Ethernet10/100/1000Mbps Laser printers, network connections, etc.


Question 3: What is a USB hub?

Answer: A hub is a USB device that includes extra ports into which other USB device can be attached. Some hubs, like the keyboard, are bus powered, deriving their power from a source on the bus to which they are attached.

Others are self-powered. These come with an AC adapter that plugs into an electrical outlet and supplies power to the hub. There are several companies that sell hubs today.

Some self-powered hubs are likely to function solely as hubs, acting as a source of power and allowing you to plug several downstream devices into them. Other devices may include a built-in hub (like the Apple USB Keyboard) that serve a primary function but also provide other ports into which another device can be connected.

Other USB FAQ's can be found in the following articles:


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