Question

Design an 8-to-1 multiplexer using only 4 -to-1 multiplexer modules without enable lines. (Do not use any additional gates.)

Answer 1

An 8-to-1 multiplexer can be designed using three 4-to-1 multiplexer modules by connecting the first two multiplexers to the initial eight inputs and using the third multiplexer as a final selector using the third selection line.

Step-by-step explanation:

To design an 8-to-1 multiplexer modules using only 4-to-1 multiplexer modules, you can proceed as follows:

• Use three 4-to-1 multiplexer modules.
• Label them as MUX1, MUX2, and MUX3.
• Connect the inputs of MUX1 and MUX2 to the first four data inputs (D0 to D3 for MUX1, and D4 to D7 for MUX2) respectively.
• Connect the selection input lines (S0 and S1) of both MUX1 and MUX2 to the equivalent selection lines of the 8-to-1 multiplexer.
• The outputs of MUX1 and MUX2 become the data inputs of MUX3.
• Use the third selection line (S2) of the 8-to-1 multiplexer as the selection input for MUX3.

This will enable selection among the eight inputs using three selection lines (S0, S1, S2) where S2 will determine which of the two 4-to-1 multiplexers' outputs will be routed through MUX3 to the final output.