[BCD Addition Calculator]

Thanx Anubhav,
Iam trying to find the book!!! ;D

[BCD Addition Calculator]

Hi guys,
I'm a second year engineering student and I have to make a logic circuits project. I chose a BCD Adder and I have a circuit ready. The problem is that I need a way to give the input as since I am adding two 2-digit numbers, the number of input bits will be huge (16). Is there a way I could emulate a conventional calculator for punching in the input through a keyboard instead of having individual switches for each bit?
And just so I don't appear a TOTAL greenhorn, I haven't any idea of microprocessors or complex IC's beyond your gates and op-amps!!
Thanx