The Intel 8086 is a 16-bit microprocessor intended to be used as the CPU in a microcomputer. The term “16-bit” means that its arithmetic logic unit, internal registers, and most of its instructions are designed to work 16-bit binary words. It has 16-bit data bus and 20-bit address bus.
words will be stored in two consecutive memory locations. If the first byte of a word is at an even address, the 8086 can read the entire word in one operation. If the first byte of the word is at an odd address, the 8086 will read the first byte in one operation, and the second byte in another operation.
Following figure shows the internal block diagram of 8086 microprocessor.
The Bus Interface Unit
Instruction Queue
COMPARISION
– A data width of 2 byte is attained by the de multiplexing of AD0 to AF15 pins.
– The instruction queue is of 6 bytes.
– From the memory the fetching of a program is performed only once there are 2 byte empty in queue.
– The BIU of 8086 is not as same as in the 8088 but the EU is similar.
Features of the 8088:
– It requires a 1 byte data width which is generated after the de multiplexing of AD0 to AD7 pins.
– The instruction queue is 4-bytes.
– Program fetching is performed as soon as there is a byte empty in queue.