Design the BCD to 7-segment decoder circuit as given in the theory section. The circuit should take 4 inputs (A, B, C, D) and produce 7 outputs (a, b, c, d, e, f, g) corresponding to the seven segments of the display.

Construct a complete BCD to 7-segment display interface system. Connect the decoder outputs to a 7-segment display unit and verify that BCD inputs 0000 to 1001 correctly display decimal digits 0 to 9 on the 7-segment display.

Design a hexadecimal to 7-segment decoder that can display all 16 hexadecimal digits (0-9, A-F). Analyze the K-maps for each segment (a, b, c, d, e, f, g) and implement the optimized Boolean expressions using logic gates.

Can the BCD to 7-segment decoder be implemented using only NAND gates? If yes, explain the conversion process. If no, explain why other gates are necessary and provide an alternative implementation approach.