Chapter 4 Interfacing I/O Devices. Interfacing I/O Devices. Using I/O devices data can be transferred between the microprocessor and the outside world. This can be done in groups of 8 bits using the entire data bus. This is called parallel I/O.
WRInterfacing the LEDs (Control Circuit)
MVI A, Data ;load the data to be displayed
OUT FF ;send the data to output port FF
RDInterfacing the Switches (Control Circuit)
IN 0FH ;input data from port 0F into A
INPUT: IN 0FH