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.
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
Relays are bidirectional 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.
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.
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.
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
Its not, a diode is unidirectional.
Bidirestional
So that the processor can both read and write data.