The BCD adder adds the two BCD digits and produces a result which is also a BCD number.

It contains four inter connected full-adders and the look ahead carry circuitry needed for high speed operatio.

The 7483 is a TTL medium scale  integrated circuit.

The inputs to this IC are two $-bit numbers A3A2A1A0 and B3B2B1B0 and carry Cin into the LSB position.

The outputs are the sum bits S3S2S1S0 and carry Cout output of the MSB position.