Data flow is always bidirectional my friend, don't confuse.
Relays are bidirectional devices.
The control bus is a unidirectional bus because it can receive the data from any kind of inputs and send back the output. This whole process is done by the data buses.
Its not, a diode is unidirectional.
Bidirestional
since data can be read /write from/to the microprocessor, hence data bus is bidirectional. if data is required read from microprocessor then it will be pointing to a memory location by the address bus, by indicating which location data its required to read. similarly to write a data to a location, again the microprocessor will be to that particular location by holding that address in address bus. hence it will be unidirectional.
The arc is the line that connects two nodes in a network. There are two kinds of arcs; unidirectional and bidirectional. Unidirectional means the flow is in one direction (if you are studying for example the water supply system in a city). Bidirectional means the flow is in both directions. Network models are very helpful to simplify real problems.
A unidirectional amplifier & a Bidirectional amplifier
Unidirectional TVS: A TVS device with asymmetrical current versus voltage (I−V) properties. A unidirectional TVS is best suited for protecting circuit nodes whose signals are unidirectional or always above or below the reference voltage, usually ground. Bidirectional TVS: A TVS device with symmetrical I−V properties. A bidirectional TVS is best suited for protecting electrical nodes whose signals are bidirectional or can have voltage levels both above and below the reference voltage, usually ground
The optical fiber can be used both as unidirectional and bidirectional. The main application of optical fiber is in long-distance links, so there exists no need to employ them as unidirectional. For each direction different wavelengths are used to modulat the signals. At the same time many bidirectional signals can travel through the same optical fiber.
The address bus is unidirectional becos address information is always given by microprocessor to i/o devices. The data bus is bidirectional bcos it takes the data from other devices & also give the data to other i/o devices
A bi-directional buffer includes first and second unidirectional buffers connected for retransmitting signals in opposite directions between first and second buses. When an external bus driver pulls the first bus low, the first unidirectional buffer pulls the second bus low and generates a signal inhibiting the second unidirectional buffer from actively driving the first bus. When the external bus driver allows the first bus to return to the high logic level, the first unidirectional buffer temporarily supplies a high charging current to the second bus to quickly pull it up. Similarly, when an external bus driver pulls the second bus low, the second unidirectional buffer pulls the first bus low and generates a signal inhibiting the first unidirectional buffer from actively driving the second bus. When the external bus driver allows the second bus to return to the high logic level, the second buffer temporarily supplies a high charging current to the first bus to quickly pull it up. The bi-directional buffer includes a register for storing and reading out data representing successive logic states of a signal on the first bus, thereby providing a history of data appearing on the bus
The presence of sieve plates in phloem tubes allows for bidirectional flow, which contradicts the unidirectional flow proposed by the pressure flow model. The sieve plates also enable some sieve elements to be blocked while others remain functional, challenging the notion of a continuous flow in the phloem.