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8086 Microprocessor: Introduction, Features, Components

In this tutorial, we are going to discuss the 8086 microprocessors. We will first define this microprocessor, its features and will explain its working. While doing so we are going to discuss the number of bits it functions on, the amount of memory it carries and about the different components it consists of. By Monika Sharma Last updated : May 15, 2023

Introduction to 8086 Microprocessor

The 8086 Microprocessor is an enhanced version of the 8085 Microprocessor, it was developed to overcome the drawbacks of the 8085 Microprocessor in 1976. It is a 16-bit-based Microprocessor that has 20 address lines and 16 data lines.

The 8086 Microprocessor supports both operation modes. The maximum operation mode is useful for systems which have multiple processors and the minimum operation mode is useful for the systems which have a single processor.

Features of 8086 Microprocessor

The most important features of 8086 microprocessors are as follows -

1. The 8086 microprocessor is a 16-bit microprocessor. What this means is that the ALU and the internal registers work with 16 bit of binary data at a time.
2. It has 16 bits of the data bus. Because of this, the 8086 can read or write either 16 bit or 8 bit of data at a time.
3. The 8086 microprocessor has 20 bits of address lines that can access 220 address locations.
4. Each memory location is a byte-addressable memory location.
   Therefore, the total amount of memory that the 8086 microprocessor contains = 2²⁰ bytes = 1 MB
   Therefore, the 8086 can access up to 1 MB of memory.
5. It works in the frequency range of about 5-10 MHz. (There are 3 versions of the 8086 microprocessor and each of them works in a different frequency range.)
6. The 8086 microprocessor works in 2 modes:
   • Maximum mode
   • Minimum mode
7. The instruction queue of the 8086 microprocessor is of 6 bytes of length. Therefore, the 8086 microprocessor can pre-fetch up to 6 instructions from the memory and queue them in order to speed up the instruction execution.
8. The 8086 microprocessor can perform only fixed-point arithmetic instructions. It means that the floating-point operations cannot be performed by it. This is a drawback of the 8086 which was later eliminated in the further series of Intel processors.

Components of 8086 Microprocessor

The following are the components of an 8086 microprocessor:

• The 8086 microprocessor consists of two main blocks:
  1. Bus Interface Unit (BIU)
  2. Execution Unit (EU)
• The Bus Interface Unit (BIU) consists of the following components:
  1. Instruction Queue
  2. Segment Registers
  3. Instruction Pointer (IP)
• The Execution Unit (EU) consists the following:
  1. Arithmetic Logic Unit (ALU)
  2. Control Unit
  3. General Purpose registers
  4. Index registers and pointers (except IP)
  5. Flags and Operands

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