The bus that can only transmit signals from the cpu in one direction is

1 and "address bus AB" are specially used to transmit addresses. Because the address can only be transmitted from CPU to external memory or I/O port, the address bus is always unidirectional and tri-state, which is different from the data bus. "Control bus CB" is used to transmit control signals and timing signals.

2.( 1) DataBus (DB, Databus) Data bus is used to transmit data information. This is a two-way bus. CPU can read data from memory or input device through DB, and can also send internal data to memory or output device through DB.

3. The data bus and the control bus are bidirectional, and the address bus is unidirectional, just from the CPU to the I/O port. The "address bus AB" is dedicated to transmitting addresses. Because the address can only be transmitted from CPU to external memory or I/O port, the address bus is always unidirectional and tri-state, which is different from the data bus.

4. The bus in microcomputer is divided into data bus, address bus and control bus, which transmit data signal, address signal and control signal respectively. Data bus and control bus are bidirectional transmission, that is, they can be from CPU to I/O port or from I/O port to CPU. The address bus is transmitted in one direction, only from CPU to I/O port.