Construct, explain and identify all the input$/$output pins for the $8$:$1$ Multiplexer, with complete wiring connections and truth table.

Design $26$:$1$ Mux $($Using $8$:$1$ & $4$:$1$ Mux's, Exact identification and connection of the select lines is essential for full credit$)$

Construct MOD$26$ up counter. Describe all the pins, with required feedback.