1. 8086 processor

2. 8085 Vs 8086 8086 8085 16 bit processor developed in 1978
8-bit processor created in 1977
Consists of 6200 transistors
16 bit address line which can access 64KB memory location
No. of flags are 5
Pipelining Concepts is not used
Instruction Q does not exist only sequential execution available
Only 5 types of addressing modes
8086
16 bit processor developed in 1978
29000 transistors approx.
20 bit address bus which can access 1MB memory location
No. of flags are 9
8086 uses pipelining
6 byte queue in BIU available
8 types of addressing modes available

3. Architecture of 8086

20. S

21. Pipelining
Fetching the next instruction while the current instruction is under execution is called pipelining.
Load
Execute
Store
Load:
read instruction from memory
Execute:
execute instruction
Store:
store instruction memory/register

22. Traditional Pipeline Concept
Laundry Example
Ann, Brian, Cathy, Dave each have one load of clothes to wash, dry, and fold
Washer takes 30 minutes
Dryer takes 40 minutes
“Folder” takes 20 minutes A B C D

23. Traditional Pipeline Concept
6 PM 7 8 9 10 11
Midnight
Time 30 40 20 30 40 20 30 40 20 30 40 20
Sequential laundry takes 6 hours for 4 loads
If they learned pipelining, how long would laundry take? A B C D

24. Traditional Pipeline Concept
6 PM 7 8 9 10 11
Midnight
Time T a s k O r d e 30 40 20 A
Pipelined laundry takes 3.5 hours for 4 loads B C D

25. Use the Idea of Pipelining in a Computer
Fetch + Execution T
ime I I I 1 2 3 T
ime
Clock cycle 1 2 3 4 F E F E F E 1 1 2 2 3 3
Instruction I F E
(a) Sequential execution 1 1 1 I F E 2 2 2
Interstage buffer B1 I F E 3 3 3
Instruction Ex
ecution
fetch
unit
(c) Pipelined execution
unit
Figure . Basic idea of instruction pipelining.
(b) Hardware organization

26. Use the Idea of Pipelining in a Computer
Fetch + Decode
+ Execution + Write

29. Flag register

31. Pin diagram of 8086