How Binary Numbers are Used to Store Data

How Disk Drives, DVDs, CDs and Memory Devices Work

Mar 3, 2009

DVDs, CDs, Solid State memory devices and disk drives are found almost everywhere. This article explains how information is stored using the binary number system.

The vast amount of information that is produced and stored every day is staggering. Most of the data are stored on Hard Disk Drive (HDD), Compact Disk (CD), Digital Versatile Disk (DVDs), or Solid State Devices (SSD).

General Principle of Data Storage

The most common method of storing data on any device is to use the binary number system. The word "binary" refers to the two states used in the devices. In the binary number system the digits used are 0 and 1.

The use of only two states is very convenient, because there are various ways to represent just two alternatives. For example, "up" and "down" bumps, North and South magnets, opaque and transparent materials, are all ways to represent the two possible states.

How Binary is Used to Represent Data

Information stored on everyday devices is stored as a set of binary numbers. The type of information is generally a number, a character, or a unit of information on an image, called a pixel.

How Decimal Numbers are Converted to Binary Numbers

How Keyboard Characters are Stored as Binary Numbers

There are several methods available, but the ASCII code set will be used here. The ASCII coding system assigns a number to every character. For example, the letter “A” in upper case has the code 65. The character for the digit “9” is 71. The question mark “?” has the code 63. So in binary representation:

How Images are Stored as Binary Numbers

The smallest unit in an image is called a pixel. Each pixel is given a value represented by three numbers, one for each of red, green and blue. The numbers vary from 0 to 255. As for numbers and characters, an 8-bit sequence gives 256 possible values for each color in the pixel. In the RGB (Red Green Blue) system, pure white is made up from 100% red plus 100% blue plus 100% green.

The code for white is therefore 111111111111111111111111. Pure blue is 100% blue, and 0% of the other colors, and so it has the code 000000000000000011111111.

Summary of How Binary Numbers are Used to Store Data

The binary number system is the keystone of data storage. All of the main data storage devices used are able to convert the data to be stored into a binary number, whether the data format is numeric, text or graphical. DVDs and CDs use the methods described in How DVDs and CDs Store Data and disk drives use the method described in How Disk Drives Store Data.

The copyright of the article How Binary Numbers are Used to Store Data in PC Hardware is owned by Martin Bell. Permission to republish How Binary Numbers are Used to Store Data in print or online must be granted by the author in writing.

Oct 2, 2009 10:58 AM

Guest :

Nice article to begin with.. but was looking for a more in-depth analysis.. could you direct me to more in depth discussions on the topic.

Thanks

NetEmp

Oct 3, 2009 3:36 AM

Martin Bell :

If you want to know the physics of the data storage methods, then the articles How DVDs and CDs Store Data, How Disk Drives Store Data, and ASCII Codes for Keyboard Characters are more in-depth and can be found at:

http://everyday-chemistry.suite101.com/article.cfm/how_dvds_and_cds_store _data

http://electricitymagnetism.suite101.com/article.cfm/how_disk_drives_sto re_data

http://computerprogramming.suite101.com/article.cfm/ascii_codes_for_comm on_keyboard_characters