Some devices require that you specify the Direct Memory Access (DMA) channel that you want the adapter to use. Direct memory access permits data to be transferred between memory and a device without the intervention of the system's central processing unit (CPU). Each DMA chip on the system motherboard has eight circuits (or ``channels'') for conveying data. DMA channel 4 is reserved for use by the system. During configuration, you may choose to use any (or none) of the channels.