Work timing of an output device as shown in figure 7.11, when it is not BUSY, BUSY=0, its state signal by interface output data to peripherals, CPU and when data is added to the peripherals, must use the negative pulse data latches on peripherals, receives the data and command peripherals,
1) try to its peripherals connected to the system bus 8088,
(2) programming implementation will start 50 consecutive bytes of memory 40000 h unit of data, using the method of query output to the device,