An Introduction of Microprocessors & Microcontrollers
Microprocessors
As the technology advances, the Microprocessors are becoming one of the most useful electronics devices.
A microprocessor is defined as a multipurpose, programmable electronics device that can perform any computing task or can communicate with other peripheral devices of the chip (integrated circuit).
The most significant features of a microprocessor include:
- Programmable- it can be instructed to perform a given task within its capability.
- Multipurpose- can be used in various systems such as CPU (central processing unit) of a microcomputer, digital calculators, radar systems, printers etc.
- Clock driven- it requires clock pulse to synchronize its operations.
- Takes input as binary data- binary data is sequence of 0 & 1 bits.
- It has no in-built memory on the IC.
The microprocessor is named by combining two words- MICRO and PROCESSOR.
There are two reasons of using a Micro word:
(1) The operating frequency of 1st generation microprocessors was in MHz range. Their clock pulse period was in microsecond (µs).
(2) The channel-length of Semiconductor technology in 1970s was in µm.
The other word is Processor, which means a device that can perform a general task.
And thus microprocessor is named in 1970s, when 1st intel 4004 microprocessor was invented. It is a 4-bit microprocessor or the word-length is 4-bit (word length is the length or number of bits that a microprocessor can process at a time).
The 1st 8-bit microprocessor was intel 8008 which was invented in 1972. But the 1st 8-bit microprocessor which is successfully launched in the market is Intel 8085
Microprocessor or CPU of microcomputer consists of -ALU (Arithmetic Logic Unit), CU (Control Unit) and Registers
ALU performs various computing functions for example addition, subtraction and some logical operations such as AND, OR, NOT etc.
The microprocessor communicates with only one peripheral at a time. The timing is provided by the control unit. It also generates some control signals to maintain the flow of data between microprocessor and memory and peripherals.
In microprocessors registers are used to store data temporarily during execution of the program and are accessible to user through instructions.
In block diagram, system buses are used to carry address, data and control signals to establish communication between microprocessor and other peripherals.
Microcontrollers
Memories are externally interfaced with microprocessors, which increases size and cost of the overall system. Microcontrollers were designed with the main intention of reducing the size, cost and complexity of the systems. it took almost a decade to design a commercially successful microcontroller and it was intel 8051 invented in 1981.
Microcontroller is a portable, low power and more efficient computing device which has capability of controlling the specific task of an embedded systems.
The key features include: it is programmed only at the time of fabrication or assembling, it is clock driven and has in-built memories.
Microprocessor is the one of the building block of microcontroller and thus it can also be called as microcomputer.
It has wide area of applications such as air-conditioners, cameras, traffic light systems, artificial intelligent systems etc.
The microcontroller is constituted of CPU, memories, I/O ports, serial com ports, timers etc. The general block diagram of a microcontroller is shown in Fig.2.
Differences Between Microprocessor and Microcontroller
