Features of 8086 Microprocessor

8086 is a 16bit microprocessor

 Function of processor:

    Control the entire circuit.

    Execute the instruction.

Features of 8086:

  1. Buses:

      i. Address Bus   : 8086 has a 20 bit address bus. Hence it can access 1 MB memory.The address range for this memory is 00000 H to FFFFF H.

      ii. Data Bus       : 8086 has a 16 bit data bus i.e it can access 16bit data in one operation. Its ALU and internal data registers are also 16 bits; hence 8086 is called as a  16 bit microprocessor.

      iii. Control Bus : The control bus carries the signals essential for the various operations like Read, Write, etc.

   2. 8086 supports Pipe-lining:

                           Pipeline is process of fetching the next instruction while executing the current instruction.

                 For eg.

      Advantage of Pipe-lining:

                          Pipe-lining highly improves the performance of the system.

      Disadvantage: 

                          During execution (1st instruction) is the branch  instruction occurs (i.e Jump/call) next instruction is invalid. Then instruction and pipe-lining gets fails.

           For eg. 

                      1   E 1   (if branch  :  go to 6)

                      2   F 2    Invalid

                      3

                      4

                      5

                      6  Fetching
                  Because of that instruction (go to 6 ) other instruction gets                          invalid from F 2 to F 5.
  3. 8086 has 2 operating modes:

         Advantage of Multiprocessor:

•  Speed of processing data is faster.
• Two programs can run simultaneously.

4. 8086 provide Memory Banks:

• The entire memory of 1 MB is divided into 2 Banks of 512 KB each.
• 8086 has a 16 bit data bus hence it should be able to access 16 bit data in one operation.
• To do so it needs to read from 2 memory location as one memory location carries one byte.
• However, if both these memory locations are i the same memory chip then the address bus will have to contain two addresses at the same time , which is impossible.
• To solve this problem, the memory of 8086 is divided into two banks provides 8 bit data.
• Therefore one banks contains all even addresses called "Even banks", while the other is called "Odd bank" containing all odd address. 

   
      Ao            Operation
   0       0            R/W 16 bits from both bank
   0       1            R/W 8 bits from Higher bank
   1       0            R/W 8 bits from lower bank
   1       1            No operation (Idle).
5. 8086 supports Memory Segmentation: 

• Segmentation means dividing into logical components.
• Here the memory is divided into 4 segments (64 KB X 4) Code, Stack, Data and Extra Segment.

6. 8086 has 256 types of vectored interrupts.

7.8086 has a 16 bit I/O address: 
               It can access 2^16 I/O ports (i.e. 64 KB I/O ports).

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