Tristate buffers can be used for shared bus interfaces, bidirectional IOs and shared memory interfaces. These onchip implementations allows bi-directional IO’s to switch polarities from input to output. Also when used on external chip-memory interface, these can switch to floating or high Z outputs to allow other devices on the same shared bus to access same memory.
Tri-state buffer with ENA low is Switch open or Hi-Z, Truth Table and symbolfrom
here: The implementation in truth table allows the output to go floating without
attaining a high or low. This allows other devices connected on shared bus to drive
the bus. Tristate buffer interface to memory shared bus is next.