The document contains code for several basic digital logic components including: 1. A full adder described using signals and delays. 2. A 4:1 multiplexer using elsif statements to select the output. 3. A 4:1 multiplexer using a when statement to select the output. 4. A 1:4 demultiplexer using if/elsif statements to activate one output. 5. A full adder described behaviorally using boolean expressions. 6. A D latch with an output that follows the input on the positive clock edge. 7. A D flip-flop with an output that follows the input on the positive clock edge.