Microprocessor – 8086 Overview

The 8086 microprocessor is an improved version of the 8085 macroprocessor designed by Intel in 1976. It is a 16-bit microprocessor with 20 address lines and 16 data lines that provide 1MB of storage. It has powerful instruction sets, which provide operations such as easy multiplication and division.Microprocessor – 8086 Overview features below:-

It supports two modes of operation, i.e. maximum mode and minimum mode. Maximum mode is suitable for systems with more than one processor and minimum mode is suitable for systems with single processor.

8086 features

The most prominent features of 8086 microprocessor are as follows –

• It has an instruction queue, capable of storing six instruction bytes from memory, resulting in faster processing.

• It was the first 16-bit processor with 16-bit ALU, 16-bit register, internal data bus and 16-bit external data bus, resulting in faster processing.

• It is available in 3 versions depending on the frequency of operation –

o 8086 → 5MHz

o 8086-2 → 8 MHz

o (c) 8086-1 → 10 MHz

• It uses two stages of pipelining, namely the fetch stage and the execution phase, which improve performance.

• The fetch step can prefetch up to 6 bytes of instructions and store them in a queue.

• The execute step executes these instructions.

• It has 256 accessible interrupts.

• It contains 29,000 transistors

Comparison between 8085 and 8086 microprocessors

• Size – 8085 is an 8-bit microprocessor, while 8086 is a 16-bit microprocessor.

• Address bus – the 8085 has a 16-bit address bus while the 8086 has a 20-bit address bus.

• Memory – 8085 can reach 64Kb, while 8086 can reach 1 MB of memory.

• Instruction – Inst Inst5 does not have an instruction queue, whereas hast an६ has an instruction queue.

• Pipeline – 8085 does not support a pipeline architecture while 8086 supports a pipeline architecture.

• I / O – 8085 can detect 2 ^ 8 = 256 I / O, while 8086 can use 2 ^ 16 = 65,536 I / O.

• Cost – 8085 costs less while 8086 costs more.

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