Combining Two Different Submodule Types

Real designs mix and match different kinds of submodules, not just repeated copies of one. Here you’ll combine two different submodule types to build a small AND-OR-Invert-style structure (without the invert).

You are given two submodules:

module andgate (input in1, input in2, output out);
    assign out = in1 & in2;
endmodule

module orgate (input in1, input in2, output out);
    assign out = in1 | in2;
endmodule

Build top_module with inputs a, b, c, d and output out, computing out = (a AND b) OR (c AND d) using two instances of andgate and one instance of orgate — no direct use of & or | in top_module itself.

Interface

Notes

• Use two internal wires to carry the two AND results into the OR gate.
• This mirrors how real hierarchical designs are built from a library of heterogeneous building blocks rather than one repeated part.