37. Tri-State Buffer

module tribuf_prim (
    input  a,
    input  en,
    output y
);
    bufif1 g_buf (y, a, en);
endmodule

💡Remember

bufif1 = transparent when enable=1, else drives z.
bufif0 = transparent when enable=0, else drives z.
Tri-state buffers are used to share a bus; only one driver may be enabled at a time.
If en=x or z, output may become x/z depending on a.