Microprocessor – Types of Microprocessors & their Applications

Electrical Technology

Different Types of Microprocessors and Their Application

What is a Microprocessor?

A microprocessor is a central processing unit or the brain of a computer inside a single Integrated circuit (IC). It is made up of millions of semiconductor transistors, diodes & resistors and it is responsible for any arithmetic or logical operation. It is a digital device capable of processing any binary data given to it.

A general-purpose microprocessor consists of ALU (arithmetic logic unit), control unit and register array. The ALU’s purpose is to apply any logical or arithmetic operation on the data provided by the computer memory. The microprocessor fetches the instruction from memory and executes it sequentially. When the instruction is complete, it sends the resultant data through the output in a binary digital form.

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Evolution of Microprocessor

First Generation 4-bit Microprocessor

This is the first microprocessor invented by Intel in 1971. They named it Intel 4004 because it was a 4-bit microprocessor

Second Generation 8-bit Microprocessor

The Second generation processor was an 8-bit microprocessor developed by Intel in the year 1973. It was named Intel 8008 because it was 8 bit.

Third Generation 16-bit Microprocessor

The third generation microprocessors were 16-bit microprocessors introduced in 1978 by Intel. 80286 is a 3^rd generation microprocessor.

Fourth Generation 32-bit Microprocessor

The Fourth generation microprocessors were introduced in 1985 and they were 32 bit. 80386 or also known as i386 or just 386 is the most renowned 4^th generation microprocessor.

Fifth Generation 64-bit Microprocessor

The fifth-generation microprocessor or 64-bit microprocessors were introduced in 1995 and they are being used till now. The Intel Pentium processors were based on 64-bit architecture. The recent 64-bit microprocessor use super scaling to offer high speed and high performance such as Intel dual, quad, octa-core microprocessors.

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Different Types of Microprocessors

There are different types of microprocessors designed to be used for specific purposes. It has been evolved to be used in various different applications. They are mainly classified into three major types;

CISC Microprocessor

CISC is an acronym for complex instruction set computer. This microprocessor is designed to execute complex instructions (a combination of multiple single instructions) which minimize the number of total instructions per program.

A complex instruction has multiple simple instructions like arithmetic operation, storing in memory, reading from memory, etc. The overall length of the program is relatively very small but due to the large size of its instruction set with many addressing modes in a single instruction, it takes multiples machine cycles to execute an instruction. Thus it reduces the execution speed of the microprocessor.

Features of CISC Microprocessor:

The instructions are complex.
The numbers of instructions are relatively more than RISC microprocessor almost 100 to 200.
It takes more than four cycles to somewhere around 120 to complete complex instructions.
The program is executed sequentially thus no feature of pipelining (parallel execution).
The instructions are executed by micro program where the complexity lies.
The instruction format and size may vary as opposed to RISC fixed instructions.
The program code in CISC is simple and short thus it uses less memory or RAM.
It put emphasis on the hardware and less on the software or programming.

RISC Microprocessor

RISC stands for Reduced Instruction Set Computer. This type of microprocessor is based on an architecture designed to execute simple instructions. The instructions are simplified to reduce the execution time. The instruction is usually completed in one clock cycle by using pipelining to execute parts of instruction in parallel. Therefore, it requires program code with more lines and more memory to store instruction. This architecture offers to execute program efficiently and quickly.

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Features of RISC Microprocessor

The instructions in RISC microprocessors are simple.
As suggested by its name, the numbers of instructions are reduced to between 30 and 40.
The instructions are simple thus it takes only one machine cycle to complete.
Pipelining (parallel execution) is fairly easy in a RISC microprocessor.
The format and size of instructions is limited and fixed.
Due to the low number of instructions, the program code lengthy and require more memory.
It put emphasis on the software or compiler and less on the load on the hardware.

Special Purpose Microprocessor

There are various types of microprocessors designed for special purposes. Here are some the special purpose microprocessor given below;

Coprocessor

The coprocessor is a type of special-purpose processor that helps the main or primary processor in processing complex tasks. It increases the performance of the primary processor by lend its processing power to reducing the load off the primary processor. These are used in graphic, complex arithmetic operation, single processing and I/O interfacing operations.

The coprocessor is physically separate from the main processor (CPU) and it works independently. They are very fast in executing a specific task because of its limited instruction set. Therefore, they cannot be used for general purpose applications like CPU.

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Transputer (Transistor Computer)

The transputer is the first general-purpose computer designed by Inmos to perform parallel computing. It also incorporates internal memory with serial communication links to communicate between processors for parallel operation.

The name Transputer is the combination of “transistor” and “computer”. The name was chosen due to its similarity with a transistor as the building block in the computer. It is the building block of parallel computer & multiple transputers connect together to form a fully functioning parallel computer.

They were designed to be used together to perform the parallel operation but a single transputer has the essential circuitry to work on its own. Examples of transputers are Inmos TPCORE, T400, T100, etc.

DSP (Digital Signal Processor)

The DSP or digital signal processor is a type of microprocessor specifically designed to process any signal. The architecture of DSP is fairly optimized to process signals in applications such as audio processing, speech recognition, image processing, radar, sonar, smartphones, etc.

The main objective of DSP is to convert between analog and digital signal (known as ADC & DAC) and process them by filtering, compressing & applying various algorithms in digital format. It can process multiple signals at a time in parallel operation.

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Input/Output Processor (IOP)

Input/output Processor or IOP is a special type of processor designed to control and manages the input and output tasks of a computer. They have direct access to the memory and are similar to the CPU except they only process I/O peripherals such as a mouse, keyboard, printer, display unit, etc.

The CPU and IOP acts as master and slave, the CPU sends the instruction for operation and the IOP execute it.

Graphics Processors

The graphic processor or Graphics Processing Unit (GPU) is a special type of processor specifically designed to accelerate the process of creation of images. The graphic processor executes the instructions in parallel which is the reason it is faster than the CPU. They are mostly used for rendering images in CGI (computer-generated imagery) or in video games. They are used in display devices such as smartphones, computers, gaming consoles, etc.

The GPU contains a graphic processor with other essential components like ram and cooling components. NVidia Corporation and ATI technologies are some of the companies that develop GPU for gaming, 3d animation and rendering, video editing, and CGI, etc.

Bit-Slice Microprocessors (BSM)

Bit-Slice Microprocessor or BSM is a special type of microprocessor whose main purpose is to form a microprocessor of desired word size by combining identical BSMs. It is available in 2-bit, 4-bit, 8-bit, 16-bit and 32-bit word size. And two or more than two identical BSMs are cascaded together to form a processor of conventional (8,16,32) or unconventional (6,10,12) word size.

Bit-Slicing means that the microprocessor is made from modules of identical microprocessors with a smaller bit size. Its main purpose is to increase the bit size of a microprocessor to our desired width.

Scalar and Superscalar Microprocessors

The scalar microprocessor can process one set of data at a time. It can execute only one instruction in a single clock cycle.

The Superscalar microprocessor is a type of microprocessor that can execute more than one instruction or task at a single time. It has multiple execution units that are used to process multiple instructions in parallel. These execution units are not processors but they are various ALUs inside the superscalar microprocessor.