It is a microprocessor (an electronic circuit built on a semiconductor wafer/slab) that is commonly known as the Processor and is termed as the Central Processing Unit of a computer system. It is an electronic chip that processes information based on the inputs. It is able to manipulate, retrieve, store and/or display information in binary form. Every component in the system operates under the instructions directly or indirectly from the processor.
The first microprocessor was developed in the 1960’s after the discovery of the semiconductor transistor. An analog processor or a computer large enough to fill a room completely could be miniaturized using this technology to the size of a thumbnail. Intel released the world’s first microprocessor Intel 4004 in 1971. Since then it has had a tremendous impact on the human civilization, by advancing the computer technology.
A processor executes instructions at a frequency determined by an oscillator, which acts as the clocking mechanism for the circuit. At the peak of each clock signal, the processor executes a single elementary operation or a part of an instruction. The speed of the processor is determined by this clock speed. Also, Cycles per Instruction (CPI) gives the average number of cycles required to execute an instruction for the processor. The processors with lower CPI values are faster than the one with higher CPI values.
A processor consists of several interconnected units. Cache memory and register units, control unit, execution unit, and bus management unit are the main components of a processor. Control unit links the incoming data, decodes it, and passes it to execution stages. It contains subcomponents called the sequencer, ordinal counter, and instruction register. Sequencer synchronizes the rate of instruction execution with the clock speed and it also passes the control signals to other units. Ordinal counter retains the address of the currently executing instruction and the instruction register contains the subsequent instructions that are to be executed.
The execution unit carries out the operations based on the instructions. Arithmetic and Logic unit, floating point unit, status register, and accumulator register are the subcomponents of the execution unit. Arithmetic and Logic Unit (ALU) perform basic arithmetic and logic functions, such as AND, OR, NOT and XOR operations. These operations are carried out in binary form subjected to Boolean logic. Floating point unit carries out operations related to floating point values, which are not carried out by the ALU.
Registers are small local memory locations inside the chip that temporarily stores the instructions for the processing units. Accumulator register (ACC), status register, instruction register, ordinal counter, and buffer register are the main types of registers. Cache is also a local memory that is used to temporarily store the information available in the RAM for faster access during the operations.
Processors are built using different architectures and instruction sets. An instruction set is the sum of basic operations that a processor can accomplish. Based on the instruction sets the processors are categorized as follows.
• 80×86 family: (“x” in the middle represents the family) 386, 486, 586, 686, etc.
• ARM
• IA-64
• MIPS
• Motorola 6800
• PowerPC
• SPARC
There are several classes of Intel microprocessor designs for computers.
386 : Intel Corporation released the 80386 chip in 1985. It had a 32-bit register size, a 32-bit data bus, and a 32-bit address bus and was able to handle 16MB memory; it had 275,000 transistors in it. Later i386 was developed into higher versions.
486, 586 (Pentium), 686 (Pentium II class) were advanced microprocessors designed based on the original i386 design.
What is the difference between Processor and Microprocessor?
Processor is the same device termed as the Microprocessor; in fact, processor is a shortened term for microprocessor.