The CPU starts a เส้นทาง cycle by sending the address (of memory or port) on the address เส้นทาง. All the subsystems connected to the เส้นทาง decode this address to find out whether it is being addressed. Only the addressed subsystems will get logically connected to the เส้นทาง and others do not interfere. The CPU indicates the type of เส้นทาง cycle by sending the appropriate control signal (memory read, memory write, I/O read ,I/O write) on the control เส้นทาง. In a given เส้ยทาง cycle, the CPU sends one control signal which distinctly identifies the type of เส้นทาง cycle. Memory responds to memory read or memory write whereas I/O ports respond to I/O read or I/O write. During output bus cycles, CPU puts data on the data เส้นทาง and the addressed subsystem takes it. During input เส้นทาง cycles, the addressed subsystem puts data on data เส้นทาง and the CPU takes (reads) it.