MAX232, MAX232A 5V RS232 transceiver. To operate, connect two capacitors to the C1 and C2 pins, one between the V- and GND, and one between V+ and GND. For the MAX232, capacitors should be 10uF, for the MAX232A 100nF is enough. +----------+ C1+ |1 +--+ 16| VCC V+ |2 15| GND C1- |3 14| T1out C2+ |4 MAX 13| R1in C2- |5 232 12| R1out V- |6 11| T1in T2out |7 10| T2in R2in |8 9| R2out +----------+ [This information is part of the GIICM]