Language of the machine: 8086

8086 is a 16bit N-Channel, HMOS Microprocessor.

• It Consumes less power.
• It draws 360 mA on 5 Volt.
• It is manufactured for standard temperature range 32’f – 180’f as well as extended temperature range from 40’f – 180’f.
• Its clock frequencies for different versions are 5, 8 and 10 MHz.
• It is built on single semiconductor chip and packaged in 40 pin IC package. The type of package is DIP (Dual Inline Package).
• It uses 20 address lines & 16 data lines.
• It can directly address upto 220 = 1Mbit of memory.
• 16 bit data word is divided into low order byte & high order byte.
• 20 address lines are multiplexed lines – 16 low address lines are time multiplexed with data & 4 high address lines are time multiplexed with status signals. 

8086 CPU is divided into independent Functional Parts:

1. Bus Interface Unit (BIU)
2. Execution Unit (EU)
 

•  BIU sends out addresses, fetches instructions from memory, reads data from ports & memory and write data to ports & memory. • It handles all transfers of data & addresses on buses or execution unit.

• EU tells BIU where to fetch instruction or data from & decodes instructions & execute instructions.
• EU contains control circuitry which direct internal operations, decoder in EU translates instructions fetched from memory into series of actions which EU carries out.
• EU has 16 bit ALU which can add, subtract, AND, OR, XOR, increment, decrement, complement or shift binary numbers.
• A 16 bit register in EU has 9 active flags where flag is a flip-flop that indicates some conditions produced by execution of instruction produced by execution of an instruction. 

Register Organization of 8086 8086 has fourteen 16 bit registers classified as :

•  General purpose Register : Ax, Bx, Cx, Dx
•  Pointer & Index Register : SP, BP, SI, DI
•  Segment register : CS, DS, SS, ES
•  Instruction pointer & status register