It often seems as though computers must understand us because we understand the information they produce. However, computers cannot understand anything. Computers recognize two distinct physical states produced by electricity, magnetic polarity, or reflected light. Essentially, they understand whether a switch is on or off. A computer appears to understand information only because it operates at such phenomenal speeds, grouping its individual on/off switches into patterns that become meaningful to us. This article is all about how data processing is done in computers and how they convert the data into useful information.
The Difference between Data and Information
In the world of computing, data is the term used to describe the information represented by groups of on/off switches. Although the words data and information often are used interchangeably, there is an important distinction between the two words. In the strictest sense, data consist of the raw numbers that computers organize to produce information.
How do computers process data
Two components handle the data processing in a computer: the central processing unit, or CPU, and the memory (register). Both are located on the computer’s motherboard.
1- CENTRAL PROCESSING UNIT (CPU)
The CPU is an integral part of the computer which interprets the instructions and carries out the basic operations required to operate the computer. It is considered as the brain of the computer. CPU contains at least two basic parts: the control unit and the arithmetic logic unit.
The control unit is responsible for managing all the computer resources. It can be symbolized as a traffic signal directing the flow of data through the CPU, as well as to and from other devices. The control unit is the logical hub of the computer. This component of the processor directs and coordinates most of the operations on the computer. Each instruction in the instruction set is expressed in microcode—a series of basic directions that tell the CPU how to execute more complex operations.
Arithmetic Logic Unit
The Arithmetic Logic Unit (ALU) carries out two types of operations: arithmetic operations and logical operations. Arithmetic operations include addition, subtraction, multiplication, and division. Logical operations include comparisons, such as determining whether one number is equal to, greater than, or less than another number.
Each time the CPU executes an instruction for data processing, it takes a series of steps. The completed series of steps is called a machine cycle. A machine cycle itself can be broken down into two smaller cycles: the instruction cycle and the execution cycle. At the beginning of the machine cycle the CPU takes two steps:
- Fetching. Before the execution of an instruction, the control unit has to fetch commands or data from the computer’s memory.
- Decoding. Before a command can be executed, the control unit decodes the command into instructions that correspond to the CPU’s instruction set.
At this point, the CPU is ready to begin the execution cycle:
- Executing. When the command is executed, the CPU carries out the instructions in order by converting them into microcode.
- Storing. The CPU may be required to store the results of an instruction in memory (but this condition is not always required)
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2- Register (Memory)
A register is a small amount of fast temporary memory within the processor where the ALU or the CU can store and change values needed to execute instructions. A special, highspeed storage area within the CPU, that contains specific data needed by the CPU, particularly the arithmetic and logic unit (ALU). All data must be represented in a register before it can be processed.
A CPU processing the command 2 + 3 would typically require at least 04 machine cycles:
1. Fetch the number 2 from RAM, decode it, and store it in register X 2.Fetch the number 3 from RAM, decode it, and store it in register Y 3.Fetch and decode the addition instruction, then add the two numbers (currently in X & Y) and store the sum in register Z 4.Fetch and decode the instruction to display the sum, and then output the sum (currently in Z) to RAM
Along with that, there are two types of built-in memory: permanent and non-permanent. Some memory chips retain the data they hold, even when the computer is turned off. This type of permanent memory is called nonvolatile. Other Chips lose their contents when the computer’s power is shut off. This type of non-permanent memory is called volatile. Learn more about computer memory here.
This is the basic cycle of how computers process data, how all the instructions are fetched, decoded, executed, and stored so that the processor performs all the required tasks. Although the process is complex, the computer can accomplish it at an incredible speed, translating millions of instructions every second. In fact, CPU performance is often measured in millions of instructions per second (MIPS).