In microprocessor, a bus refers to a set of electrical connections or pathways that enable communication between different components within the processor and between the processor and external devices.

System Bus

The system bus encompasses the address bus, data bus, and control bus collectively. It serves as the primary communication pathway within the microprocessor and between the microprocessor and other system components.

1 Address Bus:

• The address bus is responsible for carrying memory addresses generated by the microprocessor. These addresses specify the location in memory where data is to read from or written to.
• The width of the address bus determines the maximum memory capacity that the microprocessor can address. For example, a 16-bit address bus can address up to 2^16 = 65536 => 64 KB of memory.

2 Data Bus:

• The data bus is used to transfer actual data between the microprocessor and memory or other devices. It carries binary data in parallel between the microprocessor and memory.
• The width of the data bus determines the maximum amount of data that can be transferred in a single operation. For example, a 32-bits data bus can transfer 32 bits (or 4 bytes) of data at a time.

3 Control Bus:

• The control bus consists of various control signals that govern the operation of the microprocessor and coordinate data transfers. These signals include read/write, interrupt signals, and clock signals.
• Control signals on the control bus are used to indicate the types of operation (read or write), initial data transfers, and synchronize operation within the microprocessor.