Introduction - If you have any usage issues, please Google them yourself
multiple switch state instructions shown in Figure 4.3.1. AT89S51 SCM P1.0- P1.3 then four LED L1- L4, P1.4- P1.7 then switch the four K1- K4, programming will switch the state to reflect on the light-emitting diode. (Closed switch, the corresponding lights, switches off, the lights corresponding to eliminate).