Which of the three system buses is bidirectional?

1. The CPU may need to read data from main memory or write data to it. 2. Because traffic must flow both ways, the data bus is bidirectional. 3. The CPU only ever sends an address out, never receives one, so the address bus runs one way. 4. Control signals likewise travel outward from the CPU. 5. Hence the control bus and address bus are unidirectional, and only the data bus is not. _Source: NCERT Computer Science Class 11, Ch 1 'Computer System', S1.4 Data Transfer between Memory and CPU_