What is a Microprocessor?
Computer's Central Processing Unit (CPU) built on a single Integrated Circuit (IC) is called a microprocessor.
A digital computer with one microprocessor which acts as a CPU is called microcomputer.
It is a programmable, multipurpose, clock -driven, register-based electronic device that reads binary instructions from a storage device called memory, accepts binary data as input and processes data according to those instructions and provides results as output.
The microprocessor contains millions of tiny components like transistors, registers, and diodes that work together.
Block Diagram of a Microcomputer
A microprocessor consists of an ALU, control unit and register array. Where ALU performs arithmetic and logical operations on the data received from an input device or memory. Control unit controls the instructions and flow of data within the computer. And, register array consists of registers identified by letters like B, C, D, E, H, L, and accumulator.
Evolution of Microprocessors
We can categorize the microprocessor according to the generations or according to the size of the microprocessor:
First Generation (4 - bit Microprocessors)
The first generation microprocessors were introduced in the year 1971-1972 by Intel Corporation. It was named Intel 4004 since it was a 4-bit processor.
It was a processor on a single chip. It could perform simple arithmetic and logical operations such as addition, subtraction, Boolean OR and Boolean AND.
I had a control unit capable of performing control functions like fetching an instruction from storage memory, decoding it, and then generating control pulses to execute it.
Second Generation (8 - bit Microprocessor)
The second generation microprocessors were introduced in 1973 again by Intel. It was a first 8 - bit microprocessor which could perform arithmetic and logic operations on 8-bit words. It was Intel 8008, and another improved version was Intel 8088.
Third Generation (16 - bit Microprocessor)
The third generation microprocessors, introduced in 1978 were represented by Intel's 8086, Zilog Z800 and 80286, which were 16 - bit processors with a performance like minicomputers.
Fourth Generation (32 - bit Microprocessors)
Several different companies introduced the 32-bit microprocessors, but the most popular one is the Intel 80386.
Fifth Generation (64 - bit Microprocessors)
From 1995 to now we are in the fifth generation. After 80856, Intel came out with a new processor namely Pentium processor followed by Pentium Pro CPU, which allows multiple CPUs in a single system to achieve multiprocessing.
Other improved 64-bit processors are Celeron, Dual, Quad, Octa Core processors.
Table: Important Intel Microprocessors
Basic Terms used in Microprocessor
Here is a list of some basic terms used in microprocessor:
Instruction Set - The group of commands that the microprocessor can understand is called Instruction set. It is an interface between hardware and software.
Bus - Set of conductors intended to transmit data, address or control information to different elements in a microprocessor. A microprocessor will have three types of buses, i.e., data bus, address bus, and control bus.
IPC (Instructions Per Cycle) - It is a measure of how many instructions a CPU is capable of executing in a single clock.
Clock Speed - It is the number of operations per second the processor can perform. It can be expressed in megahertz (MHz) or gigahertz (GHz). It is also called the Clock Rate.
Bandwidth - The number of bits processed in a single instruction is called Bandwidth.
Word Length - The number of bits the processor can process at a time is called the word length of the processor. 8-bit Microprocessor may process 8 -bit data at a time. The range of word length is from 4 bits to 64 bits depending upon the type of the microcomputer.
Data Types - The microprocessor supports multiple data type formats like binary, ASCII, signed and unsigned numbers.
Working of Microprocessor
The microprocessor follows a sequence to execute the instruction: Fetch, Decode, and then Execute.
Initially, the instructions are stored in the storage memory of the computer in sequential order. The microprocessor fetches those instructions from the stored area (memory), then decodes it and executes those instructions till STOP instruction is met. Then, it sends the result in binary form to the output port. Between these processes, the register stores the temporary data and ALU (Arithmetic and Logic Unit) performs the computing functions.
Features of Microprocessor