Brief on difference between architecture of microprocessor 8085 and 8086.

2. 8085 MICROPRCESSOR

3. 8086 MICROPROCESSOR

4. Differences
• 8085 is the first commercially successful microprocessor by Intel.
• Then came 8086, intel combine with IBM and creates history.
• Obviously, 8086 is way better than 8085 in every aspect.
• Programming in 8085 is harder than 8086.
• 8085 instruction cycle works as Fetch, Decode and Execute where
8086 can decode and execute the instruction while fetching next
instruction from the memory because of pipelining.
• 8085 have one ALU while 8086 have two ALUs (one to perform
arithmetic operation and other one to generate physical address of
next instruction stored in memory ).

5. • 8086 is divided into 2 parts BIU (bus interface unit ) and EU (
execution unit).
• BIU fetch the instruction and EU will execute that instruction while
executing BIU keep fetching the instruction side by side , that’s how
8086 do two things at a time and generate output faster that 8085.

6. Property 8085 Microprocessor 8086 Microprocessor
Data Bus Size 8-Bit 16-Bit
Address Bus Size 16-bit 20-bit
Clock Speed 3MHz Varies in range 5.8 – 10 MHz
Duty Cycle for clock 50% 33%
Flags It has 5 flags (Sign, Zero, Auxiliary Carry, Parity, Carry) It has 9 flags (Overflow, Direction, Interrupt. Trap, Sign, Zero,
Auxiliary Carry, Parity, Carry)
Pipelining Support Does not support Supports
Memory Segmentation supports Does not support Supports
Number of transistors Nearly 6500 Nearly 29000
Processor type Accumulator based General Purpose register based
Presence of Minimum and Maximum mode Not present Present
Number of processors Only one processor is used More than one processor is used. Additional processor
(external) can also be employed
Memory Size 64KB 1MB
Instruction No multiplication and division instruction Multiplication and Division operations are present
Instruction Queue Support Does not support Supports
Arithmetic support Only integers and decimal values Integers , decimal and ASCII values
Input / output devices 2^8 = 256 IO devices 2^16 = 65536 IO devices

7. NAME -VARUN GAUTAM
ENROLL NO. – 45013202818
CLASS – ECE-2(B)