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.
Data flow is always bidirectional my friend, don't confuse.
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 data should be either WRITTEN to a memory or should be READ from a memory (both direction)and so the data bus is bidirectional.
Relays are bidirectional devices.
The control and high order address buses are unidirectional.
A bus in this context is a data route which can carry data in both directions.
Unidirectional buffer allows data to flow in only one direction, either from input to output or from output to input. Bidirectional buffer allows data to flow in both directions, enabling communication between two devices or systems bidirectionally.
A data bus is bidirectional because the processor needs it to both read and write. Also, in the case of the 4004, the data bus was tri-multiplexed with the 12 bit address bus and the 8 bit opcode bus.
Bidirestional
Its not, a diode is unidirectional.
So that the processor can both read and write data.