TTL I/O Interface Module enables students and practicing engineers to gain invaluable practical experience of the principles and applications of Microcontroller. The object is to connect and program an external controller, makes pins input and output and performs experiment like combination controller (AND, OR, XOR and NOT operations), sequential controller, programmable counter, multiplexers etc. The module provides buffered 12 TTL Outputs and 12 TTL Inputs. Logic state is indicated by LED'S. 12 Inputs are connected to DIP Switches and 12 outputs are connected to LED'S.