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Understanding Data Representation: Binary, Numeric, Text Codes, and Compression, Summaries of Computer Networks

Norton UniversityComputer Networks

An introduction to data representation, focusing on the conversion of information into digital data using binary digits, numeric and text codes, and data compression techniques. Learn about the importance of data representation, digitization, and the evolution of digital devices, as well as the basics of binary number systems and various text encoding schemes.

Typology: Summaries

2018/2019

Uploaded on 12/21/2019

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CSC 170 – Introduction to
Computers and Their Applications
Lecture #1 – Digital Basics
Data Representation
•Data refers to the symbols that represent people,
events, things, and ideas. Data can be a name, a
number, the colors in a photograph, or the notes in
a musical composition.
•Data Representation refers to the form in which
data is stored, processed, and transmitted.
•Devices such as smartphones, iPods, and
computers store data in digital formats that can be
handled by electronic circuitry.
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CSC 170 – Introduction to

Computers and Their Applications

Lecture #1 – Digital Basics

Data Representation

  • Data refers to the symbols that represent people, events, things, and ideas. Data can be a name, a number, the colors in a photograph, or the notes in a musical composition.
  • Data Representation refers to the form in which data is stored, processed, and transmitted.
  • Devices such as smartphones, iPods, and computers store data in digital formats that can be handled by electronic circuitry.

Data Representation

  • Digitization is the process of converting information, such as text, numbers, photo, or music, into digital data that can be manipulated by electronic devices.
  • The Digital Revolution has evolved through four phases, beginning with big, expensive, standalone computers, and progressing to today’s digital world in which small, inexpensive digital devices are everywhere.

Data Representation

  • The 0s and 1s used to represent digital data are referred to as binary digits — from this term we get the word bit that stands for bi nary digi t.
  • A bit is a 0 or 1 used in the digital representation of data.
  • A digital file, usually referred to simply as a file, is a named collection of data that exits on a storage medium, such as a hard disk, CD, DVD, or flash drive.

Representing Numbers

DECIMAL (BASE 10) BINARY (BASE 2) 0 0 1 1 2 10 3 11 4 100 5 101 6 110 7 111 8 1000 9 1001 10 1010 11 1011 1000 1111101000

Representing Text

  • Character data is composed of letters, symbols, and numerals that are not used in calculations.
  • Examples of character data include your name, address, and hair color.
  • Character data is commonly referred to as “text.”

Representing Text

  • Digital devices employ several types of codes to represent character data, including ASCII, Unicode, and their variants.
  • ASCII (American Standard Code for Information Interchange, pronounced “ASK ee”) requires seven bits for each character.
  • The ASCII code for an uppercase A is 1000001.

Representing Text

  • Extended ASCII is a superset of ASCII that uses eight bits for each character.
  • For example, Extended ASCII represents the uppercase letter A as 01000001.
  • Using eight bits instead of seven bits allows Extended ASCII to provide codes for 256 characters.

Representing Text

  • ASCII codes are used for numerals, such as Social Security numbers and phone numbers.
  • Plain, unformatted text is sometimes called ASCII text and is stored in a so-called text file with a name ending in .txt.
  • On Apple devices these files are labeled “ Plain Text .” In Windows, these files are labeled “ Text Document ”.

Representing Text

  • ASCII text files contain no formatting.
  • To create documents with styles and formats, formatting codes have to be embedded in the text.

Representing Text

  • Microsoft Word produces formatted text and creates documents in DOCX format.
  • Apple Pages produces documents in PAGES format.
  • Adobe Acrobat produces documents in PDF format.
  • HTML markup language used for Web pages produces documents in HTML format.

Representing Text

Bites and Bytes

Bit One binary digit Byte 8 bits Kilobit 1,024 or 2^10 bits Kilobyte 1,024 or 2^10 bytes Megabit 1,048,576 or 2^20 bits Megabyte 1,048,576 or 2^20 bytes Gigabit 230 bits Gigabyte 230 bytes Terabyte 240 bytes Petabyte 250 bytes Exabyte 260 bytes

Bites and Bytes

  • Use bits for data rates, such as Internet connection speeds, and movie download speeds.
  • Use bytes for file sizes and storage capacities.
  • 104 KB: Kilobyte (KB or Kbyte) is often used when referring to the size of small computer files.

Bites and Bytes

  • 56 Kbps: Kilobit (Kb or Kbit) can be used for slow data rates, such as a 56 Kbps (kilobits per second) dial-up connection.
  • 50 Mbps: Megabit (Mb or Mbit) is used for faster data rates, such as a 50 Mbps (megabits per second) Internet connection.

Bites and Bytes

  • 3.2 MB: Megabyte (MB or MByte) is typically used when referring to the size of files containing photos and videos.
  • 100 Gbit: Gigabit (Gb or Gbit) is used for really fast network speeds.
  • 16 GB: Gigabyte (GB or GByte) is commonly used to refer to storage capacity

Data Compression

  • Software for compressing data is sometimes referred to as a compression utility or a zip tool.
  • On laptops and desktop computers, the compression utility is accessed from the same screen used to manage files.

Data Compression

  • The process of reconstituting files is called extracting or unzipping.
  • Compressed files may end with a .zip, .gz, .pkg, or.tar.gz.