Universal Serial Bus (USB). A standard promoted by Intel for communication between an IBM PC and external peripherals over an inexpensive cable using biserial (in two rows or series)transmission. USB works at 12 Mbps with specific cost consideration for low cost peripherals. It supports up to 127 devices and both isochronous and asynchronous data transfers. Cables can be up to 5 meters long and it includes built-in power distribution for low power devices. It supports daisy chaining through a tiered star multidrop topology.