Systems such as the Thinking Machine CM-5 and the Meiko CS-2 have the capability of mapping the network interface into the user address space. This mapping requires that the interface accept and interpret application relative virtual addresses or that the interface represents the endpoint of a virtual channel (FIFO) that can be read from or written to, a single word at a time. The advantage is that messages can be received and sent by user level applications with no expensive traps into the kernel.