USB 1.1: FAQ (1 of 4)

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
USB	12Mbps	All of the above, and more
Ethernet	10/100/1000Mbps	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:

• Article 30651: "USB 1.1 FAQ (2 of 4)"
• Article 30652: "USB 1.1 FAQ (3 of 4)"
• Article 30653: "USB 1.1 FAQ (4 of 4)"