Universal Serial Bus

(USB) An external {peripheral} interface

{standard} for communication between a computer and external

{peripherals} over an inexpensive cable using {biserial}

transmission. USB is standard on current (1999) {Macintosh}

computers and is promoted by {Intel} as an option for the {IBM

PC} where it is supported by later versions of {Windows 95}.

USB works at 12 Mbps with specific consideration for low cost

peripherals. It supports up to 127 devices and both

{isochronous} and {asynchronous} data transfers. Cables can

be up to five metres long and it includes built-in power

distribution for low power devices. It supports {daisy

chaining} through a tiered star multidrop topology.

Before March 1996 Intel started to integrate the necessary

logic into PC {chip sets} and encourage other manufacturers to

do likewise, so widespread availability and support can be

expected starting the second half of 1997.

Because its relatively low speed USB is intended to replace

existing {serial ports}, {parallel ports}, {keyboard}, and

{monitor} connectors and be used with {keyboards}, {mice},

{monitors}, {printers}, and possibly some low-speed {scanners}

and removable {hard drives}. For faster devices existing

{IDE}, {SCSI}, or emerging {FC-AL} or {FireWire} interfaces

can be used.

{Home (http://www.teleport.com/~usb/)}.

(1997-03-15)