Q1. (i) A chemical process starts only if at least three out of four keys (X1, X2, X3, X4) are inserted. If a key is inserted and the main switch is ON the system produces a logic 1. Design a minimal circuit to produce this system using NAND-Gates (10 Marks) Explain how Component and Signal are used to code the circuit in Q1 (i). (2 Marks) (8 Marks) only. (ii) (iii) Write a VHDL code to implement the system in Q1 (i).