What Is USB 1.1?

USB 1.1 details and connector information

USB 1.1, sometimes called Full Speed USB, is a Universal Serial Bus (USB) standard, released in August 1998. The standard has been all but replaced by newer standards like USB 2.0, USB 3.0, and USB4.

There are actually two different "speeds" at which a USB 1.1 device can run at: Low Bandwidth at 1.5 Mbps or Full Bandwidth at 12 Mbps. This is considerably slower than USB 2.0's 480 Mbps and USB 3.0's 5,120 Mbps maximum transfer rates.

USB 1.0 was released in January 1996, but issues in that release prevented widespread support for USB. These problems were corrected in USB 1.1 and are the standard that most pre-USB-2.0 devices support.

USB 1.1 Connectors

Photo of a USB 1.1 Type A to Type B Cable
USB 1.1 Cable (Type A to Type B). Mediabridge
  • USB Type A: These plugs and receptacles are officially referred to as Series A connectors and are the commonly seen, perfectly rectangular USB connectors. USB 1.1 Type A connectors are physically compatible with both USB 2.0 and USB 3.0 Type B connectors.
  • USB Type B: These plugs and receptacles are officially referred to as Series B connectors and are square except for a rounding at the top. USB 1.1 Type B plugs are physically compatible with USB 2.0 and USB 3.0 Type B receptacles, but USB 3.0 Type B plugs are not backward compatible with USB 1.1 Type B receptacles.

Plug is the name given to a USB 1.1 male connector, and receptacle is what the female connector is called.

See our USB Physical Compatibility Chart for a one-page reference for what-fits-with-what.

Depending on choices made by the manufacturer, a particular USB 3.0 device may or may not work properly on a computer or other host that was designed for USB 1.1, even though the plugs and receptacles physically connect to each other. In other words, USB 3.0 devices are allowed to be backward compatible with USB 1.1 but are not required to be so.

Aside from incompatible issues, USB 1.1 devices and cables are, for the most part, physically compatible with USB 2.0 and USB 3.0 hardware, both Type A and Type B. However, no matter what newer standard some part of the USB-connected system supports, you'll never reach a data rate faster than 12 Mbps if you're using even one USB 1.1 part.

More Information on USB 1.1

The introduction of USB 1.1 is what led to computers lacking a floppy drive and legacy ports, sometimes called "legacy-free PCs."

USB 1.1 (as well as 1.0 and 2.0) uses a "speak-when-spoken-to" protocol. This means each device communicates with the host upon the host's request. This is different from the device starting communication from itself, which is supported in USB 3.0.

Per the USB 1.1 standard, low bandwidth devices (like keyboards and mice) can use a cable as long as 9 ft 10 in (3 meters). Full bandwidth devices can have a cable the same length high speed USB 2.0 devices support: 16 ft 5 in (5 meters).

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