15 Difference Between 8085 And 8086 Microprocessor

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What Is 8085 Microprocessor?

The Intel 8085 is an 8-bit microprocessor designed by Intel in March 1977 using NMOS technology. During its operation, data is stored in the accumulator and temporary registers. Also, the output of the operation is stored in the accumulator and in accordance with the outcome generated; the flags get set and reset. Thus, this microprocessor is commonly described as accumulator based processor.

 8085 microprocessor is similar to the 8080 microprocessor, with two additional instructions added for its serial I/O and interrupt features. The 8085 architecture consists of control unit, ALU, registers, accumulator, flags, program, and program counter, stack pointer, instruction register, memory address register, control register etc. It is used in washing machines, microwave ovens, mobile phones etc.

The arithmetic and logic unit of 8085 microprocessor is able to perform operations like add, subtract, compare, complement, increment, decrement, shift, AND, OR, X-OR.

Also Read: Difference Between Micro-controller And Microprocessor

What You Need To Know About 8085 Microprocessor

  1. 8085 microprocessor is accumulator based processor.
  2. The size of data bus in 8085 microprocessor is 8-bit. Usually data bus size specifies the amount of data that can be fetched by the data bus in one cycle.
  3. The address bus size of 8085 microprocessor is 16-bit.
  4. The clock speed of 8085 microprocessor is 3.072 MHz.
  5. The flag register in 8085 microprocessor contains 5 flags that is, Sign Flag, Zero Flag, Auxiliary Carry Flag, Parity Flag and Carry Flag.
  6. 8085 microprocessor does not support pipe-lining.
  7. 8085 microprocessor consists of less number of transistors in its structure. It is about 6500 in size.
  8. 8085 microprocessor supports a single mode of operation.
  9. 8085 microprocessor does not support memory segmentation.
  10. 8085 microprocessor supports integer and decimal.
  11. It requires less external hardware.
  12. 8085 microprocessor does not have multiplication and division instructions.
  13. 8085 microprocessor can access up to 64KB memory.
  14. 8085 is a single processor configuration microprocessor.
  15. The instruction queue is absent in 8085 microprocessor.

What Is 8086 Microprocessor?

8086 Microprocessor is an enhanced version of 8085 Microprocessor that was designed by Intel in 1976. It is a 16-bit Microprocessor having 20 address lines and 16 data lines that provides up to 1 MB storage. Along with the operation performed by the ALU of the 8085 microprocessor, the arithmetic and logic unit of 8086 microprocessor consists of powerful instruction set, which provides operations like multiplication and division easily.

More importantly, 8086 microprocessor is made up of two separate operating units that work independently:

  • BUS Interface Unit (EU) which is responsible for fetching the instructions from the memory or 1/o device.
  • Execution Unit (EU) which executes the perfected instructions present in the instruction queue.

8086 can operate as single processors as well as a multi-processor system and thus supports two modes of operation i.e Maximum mode and Minimum mode. Maximum mode is suitable for system having multiple processors and Minimum mode is suitable for system having a single processor.

What You Need To Know About 8086 Microprocessor

  1. 8086 microprocessor is a general purpose register based processor.
  2. The size of the data bus in 8086 microprocessor is 16-bit.
  3. The size the address bus in 8086 microprocessor is 20-bit.
  4. The clock speed in 8086 microprocessor was initially limited to 5MHz but it goes up to 10 MHz nowadays.
  5. The flag register in 8086 microprocessor contains 9 flags that is, Overflow Flag, Direction Flag, Interrupt Flag, Trap Flag, Sign Flag, Zero Flag, Auxiliary Flag, Carry Flag and Parity Flag.
  6. The microprocessor supports pipe-lining as it has two independent units; the Execution unit (EU) and Bus Interface Unit (BIU).
  7. 8086 microprocessor holds a very large number of transistors in its structure. It is about 29000 in size.
  8. 8086 microprocessor supports two modes of operation, that is minimum and maximum mode.
  9. 8086 microprocessor supports memory segmentation.
  10. 8086 microprocessor supports integer, decimal and ASCII arithmetic.
  11. It requires more external hardware.
  12. 8086 has multiplication and division instructions.
  13. 8086 can access up to 1MB of memory.
  14. 8086 is a multi-processor configuration microprocessor.
  15. The instruction queue is supported in 8086 microprocessor.

Similarities

  • Both 8085 and 8086 are two major microprocessor designed by Intel.
  • They both operate at higher clock speed and consists of more memory.

Also Read: Difference Between Maskable Interrupt And Non-Maskable Interrupt

Difference Between 8085 And 8086 Microprocessor In Tabular Form

BASIS OF COMPARISON   8085 PROCESSOR CESSOR
Processor 8085 microprocessor is accumulator based processor.   8086 microprocessor is a general purpose register based processor.  
Size Of Data Bus The size of data bus in 8085 microprocessor is 8-bit. The size of the data bus in 8086 microprocessor is 16-bit.  
Address Bus Size The address bus size of 8085 microprocessor is 16-bit.   The size the address bus in 8086 microprocessor is 20-bit.  
Clock Speed The clock speed of 8085 microprocessor is 3.072 MHz.   The clock speed in 8086 microprocessor was initially limited to 5MHz but it goes up to 10 MHz nowadays.  
Flag Register The flag register in 8085 microprocessor contains 5 flags that is, Sign Flag, Zero Flag, Auxiliary Carry Flag, Parity Flag and Carry Flag.   The flag register in 8086 microprocessor contains 9 flags that is, Overflow Flag, Direction Flag, Interrupt Flag, Trap Flag, Sign Flag, Zero Flag, Auxiliary Flag, Carry Flag and Parity Flag.  
Pipe-Lining 8085 microprocessor does not support pipe-lining.   The microprocessor supports pipe-lining as it has two independent units; the Execution unit (EU) and Bus Interface Unit (BIU).  
Number Of Transistors 8085 microprocessor consists of less number of transistors in its structure. It is about 6500 in size.   8086 microprocessor holds a very large number of transistors in its structure. It is about 29000 in size.  
Mode Of Operation 8085 microprocessor supports a single mode of operation.   8086 microprocessor supports two modes of operation, that is minimum and maximum mode.  
Memory Segmentation 8085 microprocessor does not support memory segmentation.   8086 microprocessor supports memory segmentation.  
Support For Integer And Decimal 8085 microprocessor supports integer and decimal.   8086 microprocessor supports integer, decimal and ASCII arithmetic.  
External Hardware Requirement It requires less external hardware.   It requires more external hardware.  
Multiplication & Division Instruction 8085 microprocessor does not have multiplication and division instructions.   8086 has multiplication and division instructions.  
Memory Access 8085 microprocessor can access up to 64KB memory.   8086 can access up to 1MB of memory.  
Configuration Nature 8085 is a single processor configuration microprocessor.   8086 is a multi-processor configuration microprocessor.  
Instruction Queue The instruction queue is absent in 8085 microprocessor.   The instruction queue is supported in 8086 microprocessor.  

Also Read: Difference Between Vectored And Non-Vectored Interrupts

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