What is a Microprocessor?|Definition ,Types & Meaning

What is a Microprocessor?

What is a Microprocessor?

In the computing world, the Microprocessor is known as the brain of a computer that executes different tasks with remarkable speed and efficiency. To learn in detail, let’s explore the definition and meaning of Processor. It is a computer chip that is used in all electronic devices; it is also known as the brain of the computer. It helps to process the data. Microprocessors are used for a wide variety of purposes such as controlling appliances, cars, and phones, running video games, and performing complex calculations on large sets of data. It is also called the central processing unit (CPU).it is a primary device that interprets and executes instructions. It is built over an integrated circuit comprising millions of small components like resistors, transistors, and diodes.

Integration Table

Sr#Integration LevelYearNo of Transistors in a Chip
1Small-Scale Integration (SSI1950Less than 100
2Medium-Scale Integration(MSI)1960Between 100 and 1000
3Large-Scale Integration(LSI)1970Between 1000 and 10,000
4Very Large-Scale Integration(VLSI)1980Between 10,000 and 100,000
5Ultra Large-Scale Integration(ULSI)1990Between 100,000 and 10,000,000
Integration Table

What is a Microcontroller?

A microcontroller is a small computing device that has a CPU(Central Processing Unit), a fixed amount of RAM and ROM, and other peripherals all embedded on a single chip. Keyboards, Mouse, Washing Machine, Digital Camera, Pendrive, Remote Controller, and Microwave, etc are some examples of Microcontroller.

Development of a Processor

Development of a Processor

The History of Microprocessors starts in the early 1970s when Intel cofounder Gordon Moore predicted that the number of transistors on a chip would double every year. the first microprocessor was developed by Intel in 1971 and was called 4004. It has 2300 transistors and could perform 6,000 Instructions per second. the 4004 was not successful because it lacked instructions to access memory directly and thus had to use slow external memory. In 1973, a new design emerged as the 8008 with more than 8000 transistors. The 8008 could not only add two numbers together but also do other operations like shift left or right, test for zero or negative numbers, and move data between registers.

Classification of Microprocessors

Microprocessors can be classified on the basis of the following criteria.

The History of Microprocessors starts in the early 1970s when Intel cofounder Gordon Moore predicted that the number of transistors on a chip would double every year. the first microprocessor was developed by Intel in 1971 and was called 4004.

  1. The width of the data that can be processed
  2. The instruction set

1-Classification of Microprocessors based on the data width

Depending on the data width, microprocessors can process instructions.  The microprocessors can be further classified as follows:

  • 8-bit Microprocessors
  • 16-bit microprocessors
  • 32-bit microprocessors
  • 64-bit microprocessors

2-Classification of Microprocessors based on Instruction Set

Initially microprocessors had very small instruction sets because complex hardware was expensive as well as difficult to build.i.byte instruction(opcode and operand in same code) Ex: MOV A(means move the data from A to the accumulator. This instruction set carries out the following types of operations.

  • Data transfer
  • Arithmetic operations
  • Logical operations
  • Control flow
  • input/output

As technology developed, more and more complex instructions were added to increase the functionality of microprocessors.

Types of Microprocessor

There are many different types of microprocessors, some of which are explained below.

1-Complex Instruction Set Computer(CISC)

CISC Microprocessor

They support hundreds of instructions with variable sizes. Computers supporting CISC can accomplish a wide variety of tasks, making them ideal for personal computers. Due to complex instruction not being able to be done by single instruction per cycle. Data transfer between memory to memory. MOV 1220-1240.


Intel 386, intel 486, Pentium Pro, Pentium ii & iii, and Pentium iv, Motorola 68000, Motorola 68030, Motorola 68040, etc.

2-Reduced Instruction Set Computer(RISC)

2-Reduced Instruction Set Computer(RISC)

They have a small set of highly optimized instructions with a fixed size. ADD R7,R4. Complex instructions are also implemented using simple instructions thus reducing the size of the instruction set.

Examples: Sun Sparc & Ultra Sparc, Power PC

3-Explicitly Parallel Instruction Computing(EPIC)

10-Explicitly Parallel Instruction Computing(EPIC)

It allows computers to execute instructions parallel with the help of compilers. Without using higher clock frequencies it executes complex instructions. This kind of microprocessor encodes their instructions into 128-bit bundles and each bundle has three instructions that are encoded in 41-bits each and also a 5-bit template field that contains the information about the types of instructions in a bundle and the instructions can be executed in parallel.

Examples: Intel Architecture-64 (IA-64), Intel Xeon Phi, NVIDIA Tesla

4-Bit-Slice Processors

This type of processor divides the processing of data into different components and each component handles a specific number of bits(typically 1-bit), such components are known as slices that work in parallel to process the entire data word.

Examples: AMD2900, AMD2909,AMD2910,AMD29300


A British semiconductor company INMOS developed these microprocessors in the 1980s. As clear from the name the term transputers is basically a combination of two words transistors as well as computers. These processors were developed for parallel processing.

Examples: INMOS T414, INMOS T800

6-Graphic Processors

These processors are used to render graphics and parallel processing tasks.

Examples: IntelA2786, IBM, Intel i860

7-Application Specific Integrated Circuit (ASIC)

ASICs are designed for the specific applications that provide high performance and efficiency.

Examples: ASICs used in networking equipment, Bitcoin mining ASICs.

8-Single Instruction Multiple Data (SIMD)

This is a type of parallel processing architecture that performs the same tasks/ operations on multiple data elements at a time. In simple words, a single instruction is applied to the group of data elements.

9-Symbolic Processors

Such types of processors are designed for symbolic computation. This type of computation involves manipulating symbols, in the form of mathematical expressions or equations rather than numerical values.

10-Digital Signal Processors (DSP)

Such types of microprocessors are optimized for processing signals like video, audio, and other data in real-time.

Examples: TMS320C25, Motorola 56000, National LM32900,figit2MBB8764, etc

Microprocessor vs Processor

The microprocessor is a microchip that has all the components of a Central Processing Unit(CPU) on a single integrated circuit.it is usually used in computers and other electronic devices. It is the brain of a computer and it is used to process data and perform calculations. While the processor is just one part of a computer system, it’s an important one. A processor can be thought of as an assistant for a microprocessor because it helps the microprocessor do its job by taking care of some task So that the microprocessor doesn’t have to spend time on them.

Why do we need Processors?

Processors exist to make the computer work faster. They are the brains of computers and are located on the motherboard.

Microprocessor vs Microcontroller

CPU is stand alone, like RAM, ROM, I/O , Timer are separate.CPU, Ram,ROM, I/O & Timer are all on a single chip.
These are  designed on the amount of RAM, ROM and Input/ Output ports.These are designed for fixed amount on-chip RAM, ROM, I/O Ports.
Microprocessors are expensive.For Applications in which cost, power and space are critical.
Microprocessors are Versatile(General Purpose).Microcontrollers only can be used for single purpose(Control Oriented).
High Processing Power.Low Processing Power.
High Power Consumption.Low Power Consumption.
Instruction sets focus on processing intensive operations.Instruction sets focus on control and bit level operation.
Typically uses 32/64 bit.Typically uses 8/16 bit.
Typically deep pipeline.Typically single-cycle or two stage pipeline.
Not be used in a compact system.Can be used in a compact system.
Used in personal computers.Used in washing, machines, microwave oven, etc
Based on VON Neumann architecture.Based on Harvard architecture.

Difference between Microprocessor and Microcontroller

The major difference between microprocessors and microcontrollers are: The microprocessors perform the functions of the CPU while the microcontrollers are used as the brain of the circuit.

Both of them are basically used to optimise the computing unit as per the CPU.

A microcontroller can be considered a self-contained system with a processor, memory and peripherals and can be used as an Embedded System.

The majority of microcontrollers are used today and embedded in other machinery such as automobiles, telephones, appliances, etc.

Advantages and Disadvantages of Microprocessor


  • It can be programmed to perform a number of operations.
  •  It is extremely fast and is capable of processing over 3 Billion instructions per second. 
  • It can be used to quickly move data between various memory locations


  • There is a limitation on the size of data. 
  • These mostly do not support the floating-point operation.
  • it may cause overheating of the design. 
  • It should not come in contact with any kind of external device.

Generations of Microprocessors

Generation of Microprocessor

1-First Generation

With the invention of Intel4004 in 1971, the first generation came into picture. It had only 4-bit word size and used BMOS technology. It was used in calculators, etc.

2-Second Generation

In 1972 came 8008, Motorola 6800 which were 8-bit processors. Second generation really picked up in 1974 with Intel 8080 which was 8-bit and used NMOS Technology. In 1976, intel 8085 was introduced which was 8-bit and was commercially very popular. They were higher speed but were expensive. other more popular processors in this generation are M6800 and M6810. In 1977, Motorola and Toshiba introduced well equipped IM6100 and T8190 respectively but they did not become popular.

3-Third Generation

In 1978, Intel introduced the 16-bit 8086 processor which started the third generation of microprocessors. They were designed using HMOS Technology. They had full  arithmetic execution and higher language addressing making the speed 4 times that of the second generation. Other 16-bit processors introduced were Intel 80186 & 80286, Motorola 68000 & 68010.

4-Fourth Generation

In 1981, intel introduced 80386 which was the first 32-bit microprocessor starting the fourth generation of microprocessors. They had 4-GB memory and used HCMOS fabrication. Motorola 68020 & 68030, and HP 32 were the other popular processors in this generation.


From 1995 to until now, the fifth generation has been bringing out high performance and high speed processors that make use of 64-bit processors. Such processors include Pentium, Celeron, and quad core processors.

Sr#GenerationEraChip SizeWord SizeMax Memory SizeClock SpeedCoresExamples
1First1971-73LSI4/8 bit1 KB108 KHz-200KHzSingleIntel 8080
2Second1974-78LSI8 bit1 KBUp to 2 MHzSingleMotorola 6800, Intel 8085
3Third1979-80VLSI16 bit16 MB4 MHz-6 MHzSingleIntel 8086
4Fourth1981-95VLSI32 bit4 GBUp to 133 MHzSingleIntel 80386, Motorola 68030
5Fifth1995-tillSLSI64 bit64 GB533 MHz-34 GHzMulticorePentium, Celeron, Xeon

Microprocessor Specifications

Word Size

Each instruction has a word length, Word Size is the maximum number of bits that microprocessors can process at a time. The word size is directly proportional to the processing power of the CPU. During the processing if internal registers holds data up-to 8-bits, word length is 8-bits.if it can process 16-bits at a time, then the internal registers can hold up-to 16-bits data at a time and so on. Hence a 32-bit processor is about 4-times faster than an 8-bit processor. Some examples of word size/ length are 16-bit,32-bit, and 64-bit etc.

Memory Size

Depending upon the word size, the size of RAM varies.

Clock Speed

Clock speed means number of pulses generated per second by the clock inside a computer. The clock speed indicates the speed at which the computer can execute instructions. It determines the power of microprocessors. The microprocessors have the system clock that regulates the rate at which instructions are executed and synchronises all computer components. It generates pulses which are measured in millions of cycles per second(MHz). Faster the clock, the more instructions microprocessors can execute. Nowadays microprocessors have clock speeds of several GHz.


Core is a basic computation unit of the CPU. The CPU with two, four and eight cores is called dual-core, quad-core and octa-core processors respectively.

Features of Microprocessors


Speed of frequency(Instructions per second).

Instruction Set

It is the set of instructions that the microprocessors execute . It can range from 10 instruction sets of SIMP computers to 150-200 for advanced computers.

Data Bus

How much data transferred 

For example 8085(6-bit processor), 8086(16-bit processor). In these examples 8 and 16 are data buses respectively.

Address Bus

The number of address lines which will indicate the maximum memory it can have. Memory depends upon the address lines.

For example 8086 has 20-bit address lines(Max Memory 1MB).

Control Bus

The number of control lines to control various functions.

Register Array

The number of registers and what each size register,which type of register we are using, whether we are using an 8-bit register or a 16-bit register.

Manufacturing Technology

It describes the manufacturing technology of microprocessors . which one of the technology is used in the microprocessors like PMOS, NMOS, HMOS, CMOS

Design Technology

It describes whether we are using RISC or CISCArchitecture.

Power Requirement

How much power is required to make the processor ON(Voltage & Current Requirements).