Data Representation

In computing, data can be described as any symbols that are used to represent numbers and letters. The format in which data is stored is known as data representation.

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The computer is a digital device meaning that it stores information in one of two states using binary. We must determine how to represent meaningful information, such as a name, a program instruction or an image, in binary. All information is stored in the computer using binary numbers.We all use a variety of computers throughout the day but what makes a device a computer? Not many people stop to think about what exactly makes something a computer.

computer architecture

How would you describe a computer to a person who has never seen digital technology? One of my favorite Discovery Channel shows is Alaskan Bush People.

How would you define a computer to someone who lives in the bush of Alaska? Let's meet the Brown family so you can get a better idea of who you are explaining a computer to.

Assignment: Question for Thought 1

Directions: Pretend you are having a conversation with someone who has never used digital technology. How would you describe a computer to them? Write a brief (~75 words) description of a computer. Post your description directly into the textbox in itsLearning. Do not attach a separate document and please spellcheck prior to posting.

Digital Data

When we go on vacation, we follow a road map (whether an old fashioned paper map or a GPS navigation system). Neither the navigation system nor map is the actual road that you are travelling. Instead, these items have captured some of the information about the route that is needed to accomplish the goal of getting from your home to your vacation destination. Like the map, a computer captures and represents information in a form necessary for computer processing.

The forces shaping your future are digital and you need to understand them.

Data Representation refers to the methods used internally to represent information stored in a computer. Computers store lots of different types of information including:

While is may be the way we interact with the information (see, hear, etc.), all types of information stored in a computer are stored internally in the same simple format, a sequence of 0's and 1's. Computers use numeric codes to represent all the information they store.

Text can be represented easily by assigning a unique numeric value for each symbol used in the text. For example, the widely used ASCII code (American Standard Code for Information Interchange) defines 128 different symbols (all the characters found on a standard keyboard, plus a few extra), and assigns to each a unique numeric code between 0 and 127. In ASCII, an "A" is 65," B" is 66, "a" is 97, "b" is 98, and so forth. When you save a file as "plain text", it is stored using ASCII. ASCII format uses 1 byte per character 1 byte gives only 256 (128 standard and 128 non-standard) possible characters The code value for any character can be converted to base 2, so any written message made up of ASCII characters can be converted to a string of 0's and 1's.

Graphics that are displayed on a computer screen consist of pixels: the tiny "dots" of color that collectively create a graphic image on a computer screen. The pixels are organized into multiple rows on the computer screen. In one common configuration (800 by 600 resolution), each row is 800 pixels long, and there are 600 such rows. Each pixel has two properties: its location on the screen (X and Y coordinate)and its color.

A graphic image can be represented by a list of pixels. Imagine all the rows of pixels on the screen laid out end to end in one long row. This gives the pixel list, and a pixel's location in the list corresponds to its position on the screen.

A pixel's color is represented by a binary code, and consists of a certain number of bits. In a monochrome (black and white) image, only 1 bit is needed per pixel: 0 for black, 1 for white, for example. A 16 color image requires 4 bits per pixel. Modern display hardware allows for 24 bits per pixel, which provides an astonishing assortment of 16.8 million possible colors for each pixel.

Why are Numbers Important in Computer Science?

birthdayimportant numberWhy are numbers important? Numbers are everywhere and connected to almost everything we do. We use them to measure years, months, weeks, days, hours, and seconds. We count numbers in dollars and cents. We measure numbers in feet, inches, meters and yards. So numbers must be easy. Right? After all, we learned to count almost as soon as we learned to talk in complete sentences (perhaps even before).

If I asked you to pick two numbers and only two numbers that you believe are the most important numbers in the whole wide world, which would you pick? Would you pick 0 and 1?

Perhaps a better question is why are numbers important to computers? Numbers are our past, our present, and our future. Some of the early computers were decimal machines, but modern computers are binary machines. A digital computer stores information as numbers, but those numbers are not stored as decimal numbers. Numbers within the computer are represented in binary form. A storage location within a computer cannot be empty; it must contain either a 0 or a 1.

Introduction to number systems and binary:


base 10All number systems work according to the same rules. The base value of a number system tells us how many digits we have to work with and what is the place value of each digit in a number.

The decimal number system is the most commonly used system and the most familiar one to the general public. It is also known as a Base 10 numbering system since it is based on 10 symbols: 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9. In the decimal system, every digit has its own position as well as the decimal point. For example, the number 356.74 has 4 in the Hundredths position, 7 in the Tenths position, 6 in the Units position, 5 in the Tens position, and 3 in the Hundreds position. The decimal number system is also one of the oldest known numeral system, which is historically related to Hindu-Arabic numeral system.

Assignment: Question for Thought 2

Directions: What is the importance of the number 2,147,483,647? Numbers are everywhere and connected to just about everything we do (Intrieri, 2014). What is the importance of the number 2,147,483,647? Use the World Wide Web and your research skills to figure out the answer. Prepare a short essay (~150 words) and cite a minimum of two examples that illustrate the importance of 2,147,483,647. Make sure you proofread your document and paste your summary directly into the textbox. Do not attach a separate document.

List the citations at the end (like the example below) and use parenthetical citations inside the paragraph (like illustrated in the directions above).


Intrieri, J. (April 9, 2014), Why are Numbers so Important to Us?