8085/8086 microprocessor short notes

Definition of Microprocessor-

A microprocessor is an integrated chip designed to perform computation tasks. The basic functional unit of a microprocessor includes ALU, registers and control unit. Microprocessors are classified on the basis of data size in which ALU operates.

Suppose the ALU of the microprocessor is operating on 8-bit data in one cycle then it will be an 8-bit microprocessor. Similarly, if ALU is operating on 16-bit data then it is a 16-bit microprocessor.

short notes microprocessor-8085/8086

8086 is more expensive than the 8085 microprocessor

1-The address bus size in case of 8085 microprocessor is 16-bit whereas in case of 8086 microprocessor it is of 20-bit.

2-The memory addressing capacity of 8085 is 216  or 64 KB. On the contrary, the memory addressing the capacity of 8086 is 220 i.e., 1 MB.

3-8085 operates at a frequency of about 3 MHZ. While the operating frequency of 8086 microprocessor is 5 MHz, also the advanced version of 8086 microprocessor operates at a frequency about 8 and 10 MHz also.

4-8085 microprocessor consists of less number of transistors in its structure.Whereas 8086 comparatively holds a very large number of processors in it.

Less (around 6500) 8085

More (around 29000) 8086

5-The size of the data bus specifies the amount of data that can be fetched by the data bus in one cycle. The size of the data bus in the case of 8085 microprocessor is 8-bit while in case of 8086 microprocessor, it is 16-bit.

6-.8085 supports a single mode of operation, while 8086 supports two operating modes, minimum and maximum mode.


7-There exist total 5 flags (i.e., sign, zero, auxiliary carry, parity and carry flag) in 8085 microprocessor. As against overall 9 flags (i.e., overflow, direction, interrupt, trap and rest other of 8085) are present in 8086 microprocessor.


8-8085 is a single processor configuration microprocessor. On the contrary 8086 is a multi-processor configuration microprocessor.


9-Pipelining is unsupportable by 8085. Whereas pipelining is supported by the 8086 microprocessor.


10-Instruction queue is absent in 8085 microprocessor. While as queuing is supported by 8086 it has instruction queue.


11-Memory segmentation is not supported by 8085 while it is supported by the 8086 microprocessor.


12-8085 is an accumulator based processor. On the contrary 8086 is a general-purpose register type microprocessor.

other  exam point 8085/8086 both


Processing speed1 GHz
EfficiencyLess efficient
Power consumptionHigh
ReliabilityLess reliable
UsesFinds its use in general purpose computing systems.

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