Sunday, January 24, 2021

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.
                          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
                      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).


If you have any doubts,please let me know