A method of data transfer between devices, typically a computer and its peripherals, in which all the bits associated with a character or byte are presented to the interface simultaneously on separate conductors. There are usually other parallel conductors to carry the control signals. PIO is frequently used since it is compatible with the format used within the processor and enables high rates of data transfer to be achieved. When connection over any significant distance has to be made, the cost of the conductors and the associated drive circuits becomes significant and it is then preferable to convert to a serial input/output. PIO is gradually being replaced by high-speed serial interfaces such as USB, serial ATA (serial ATA), and Firewire, which offer better performance and lower cost.