8086 processor

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

Architecture of 8086

S

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

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

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

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

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

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

Flag register

Pin diagram of 8086