These basic digital logic gate modules are suitable to verify the digital logics and verification of the truth table, based on DTL, (discrete components - diodes ,resistances & transistors) Instrument comprises of in-built  DC regulated power supply  for logic inputs, SPDT switches are provided for selecting logic '1' logic '0', LED output indicator. Connections for inputs & outputs  are brought out at socket/terminals on the front panel. Supplied with connecting leads & manuals.