Address Bus, Data Bus, Control Bus
Address Bus The 8086 CPU uses the address bus to select the desired memory or I/O device by generating a unique address which corresponds to the memory location or the location of I/O device of the system. Address bus is unidirectional and this processor has 20-bit address lines.
Data Bus To transfer data between the CPU and memory and the CPU and I/O devices, data bus is used. The data which is in the data bus can be used as instruction for the CPU, or the CPU sends data to I/O device or the CPU receive data from I/O device. Therefore, a data bus is bidirectional.
Control Bus The control bus of 8086 carries control signals which are used to specify the memory and I/O devices. The control signals of 8086 CPU are M/IO, INTA, ALE, and DEN, etc.