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Microprocessors and its Application

Definition of Microprocessor and its application
A Microprocessor is a multipurpose programmable, clock driven, register based electronic device that reads binary instructions from a storage device called memory, accepts binary data as input, processes data according to those instructions and provide results as output. The microprocessor operates in binary 0 and 1 known as bits are represented in terms of electrical voltages in the machine that means 0 represents low voltage level and 1 represents high voltage level. Each microprocessor recognizes and processes a group of bits called the word and microprocessors are classified according to their word lengths such as 8-bits microprocessor with 8-bit word and 32-bit microprocessor with 32-bit word etc.

  • A Microprocessor is a clock driven semiconductor device consisting of electronic circuits manufactured by using either LSI or VLSI technique.

A typical programmable machine can be represented by three components : MPU, Memory and I/O as shown in Figure.

A programmable machine
  • These three components work together or interact with each other to perform a given task; thus they comprise a system
  • The machine (system) represented in above figure can be programmed to turn traffic lights on and off, compute mathematical functions, or keep trace of guidance system.
  • This system may be simple or sophisticated, depending on its applications.
  • The MPU applications are classified primarily in two categories : reprogrammable systems and embedded systems
  • In reprogrammable systems, such as Microcomputers, the MPU is used for computing and data processing.
  • In embedded systems, the microprocessor is a part of a final product and is not available for reprogramming to end user.(Note by Er. Anil Sah )

Uses Of Microprocessor
In this growing world, none of the sectors are or will be away from the uses of microprocessor. Some of the fields are listed below:

  • PC, Machines, Calculator, Car, Bike, Bus etc
  • Communications Devices like Switch, Routers, Hub, Gateways, Repeater etc
  • Industrial machines like Robots.
  • Home Appliances like Bell, Fridge, A.C., Micro-oven etc.
  • Test Instruments like CRO, Oscilloscope
  • Computers like Desktops, Laptop, Servers, PDAs, Tablet PC,etc.

Evolution Of Microprocessor


  • The first commercially available Microprocessor was the Intel 4004 produced in 1971.
  • It contained 2300 PMOS transistors.
  • The 4004 was a 4-bit device intended to be used with some other devices in making a calculator.
  • In 1972 Intel came out with the 8008,which was capable of working with 8-bit words.


  • The 8008, however, required 20 or more additional devices to form a functional CPU.


  • In 1974 Intel announced the 8080, which had a much larger instruction set than the 8008 and required only two additional devices to form a functional CPU.
  • The 8080 used NMOS transistor, so it operated much faster than the 8008
  • The 8080 is referred as a Second generation Microprocessor.
  • It requires +5V, -5V and +12V supply.


  • In 1977, Intel Produced 8085, an upgrade of 8080 that required only a +5V supply
  • It was a 8 bit Microprocessor.


  • Intel Produced 8088, which was the first Microprocessor used in personal computer by IBM.
  • It has 16-bit registers and an 8-bit data bus and can address up to 1 million bytes of internal memory.


  • In 1978 Intel came out with the 8086 which is a full 16 bit Microprocessor.
  • It has a 16-bit data bus and runs faster.
  • It can address 220 or 1048576 memory locations.


  • Runs faster than the preceding processors has additional capabilities and can address up to 16 million bytes.
  • This processor can operate in real mode or in protected mode, which enables an operating system like windows to perform multitasking and to protect them from each other.


  • Has 32-bit registers and 32-bit data bus.
  • It can address up to 4 billion bytes of memory.
  • The processor supports virtual mode, whereby it can swap portions of memory onto disk.



  • Has 32-bit registers and 32-bit data bus.
  • High-speed cache memory connected to the processor bus enables the processor to store copies of the most recently used instructions and data.
  • The processor can operate faster when using the cache directly without having to access the slower memory.


  • It has 32-bit registers, a 64-bit data bus and separate caches for data and for memory.
  • The Pentium has a 5 Stage pipelined structure and the Pentium II has a 12 stage superpipelined structure.
  • This feature enables them to run many operations in parallel.


1. Ramesh S. Gaonkar, Microprocessor Architecture, Programming, and Applications with 8085, Prentice Hall
2. A. P. Malvino and J, A. Brown, Digital Computer Electronics, 3rd Edition, Tata McGraw Hill
3. D. V. Hall, Microprocessors and Interfacing - Programming and Hardware, McGraw Hill
4. 0000 to 8085 Introduction to 8085 Microprocessor for Engineers and Scientists, A. K. Gosh, Prentice Hall





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