Introduction to Computers and Their Applications: Digital Basics

Data Representation Fundamentals

• 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.

Digitization and the Digital Revolution

• 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.

Binary Digits and Digital Files

• The Os and Is used to represent digital data are referred to as binary digits - from this term we get the word bit that stands for binary digit.
• 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.

Visualizing Data Representation

O ASCII codes represent data as Os and 1s 1 1 1 0 1 0 0 0 10 101010000 Circuit boards carry data as pulses of current -. 2 VOLTS +5 VOLTS +5 +5 +2 +5 -2 -2 -2 +5 +2 +5 -2 +5 +2 +5 -2 -2 -2 -2 CDs and DVDs store data as dark and light spots .... + - + Disk drives store data as magnetized particles + + + + + + - +

Representing Numeric Data

• Numeric data consists of numbers that can be used in arithmetic operations.
• Digital devices represent numeric data using the binary number system, also called base 2.

. The binary number system only has two digits: 0 and 1. · No numeral like 2 exists in the system, so the number "two" is represented in binary as 10 (pronounced "one zero").

Decimal and Binary Equivalents

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

Character Data and Text Representation

• 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."

Character Encoding Schemes

• 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.

Extended ASCII

• 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.

Unicode and UTF-8

• Unicode (pronounced "YOU ni code") uses sixteen bits and provides codes or 65,000 characters.

. This is a bonus for representing the alphabets of multiple languages. · UTF-8 is a variable-length coding scheme that uses seven bits for common ASCII characters but uses sixteen-bit Unicode as necessary.

ASCII Character Codes

00100000 Space 00110011 3 01000110 F 01011001 Y 01101100 l 00100021 ! 00110100 4 01000111 G 01011010 Z 01101101 m 00100022 " 00110101 5 01001000 H 01011011 [ 01101110 n 00100023 # 00110110 6 01001001 I 01011100 \ 01101111 o 00100100 $ 00110111 7 01001010 J 01011101 ] 01110000 p 00100101 % 00111000 8 01001011 K 01011110 ^ 01110001 q 00100110 & 00111001 9 01001100 L 01011111 _ 01110010 r 00100111 ' 00111010 : 01001101 M 01100000 ` 01110011 s 00101000 ( 00111011 ; 01001110 N 01100001 a 01110100 t 00101001 ) 00111100 < 01001111 O 01100010 b 01110101 u 00101010 * 00111101 = 01010000 P 01100011 c 01110110 v 00101011 + 00111110 > 01010001 Q 01100100 d 01110111 w 00101100 , 00111111 ? 01010010 R 01100101 e 01111000 x 00101101 - 01000000 @ 01010011 S 01100110 f 01111001 y 00101110 . 01000001 A 01010100 T 01100111 g 01111010 z 00101111 / 01000010 B 01010101 U 01101000 h 01111011 { 00110000 0 01000011 C 01010110 V 01101001 i 01111100 | 00110001 1 01000100 D 01010111 W 01101010 j 01111101 } 00110010 2 01000101 E 01011000 X 01101011 k 01111110 ~

ASCII Text Files and Formatting

. 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".

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

Formatted Text Document Types

. 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.

Document Formatting Example

Coasters.DOCX X xmlns:wps="http://s w15 wp14"> angle brackets. fice/word/2010/wordprocessingShape" mc:Ignorable="w14 49" wirsidRPr="003E2449" w:rsidRDefault="003 E2449">Roller Coasters Who wants to save an old roller coaster ?< /w.t> Leap- the-Dips is the world's oldest roller coaster and, according to a spokesperson for the Leap-the-Dips Preservation Foundation, one of the most historically significant. Built in 1902, Leap-the-Dips is "the sole survivor of a style and technology that was represented in more than 250 parks in North America alone in the early years of the amusement industry .< /w:t>"

Bits and Bytes Terminology

• All of the data stored and transmitted by digital devices is encoded as bits.
• Terminology related to bits and bytes is extensively used to describe storage capacity and network access speed.
• The word bit, an abbreviation for binary digit, can be further abbreviated as a lowercase b.
• A group of eight bits is called a byte and is usually abbreviated as an uppercase B.

Quantifying Digital Data

• When reading about digital devices, you'll frequently encounter references such as 90 kilobits per second, 1.44 megabytes, 2.8 gigahertz, and 2 terabytes.
• Kilo, mega, giga, tera, and similar terms are used to quantify digital data.

Units of Digital Measurement

Bit One binary digit Byte 8 bits Kilobit 1,024 or 210 bits Kilobyte 1,024 or 210 bytes Megabit 1,048,576 or 220 bits Megabyte 1,048,576 or 220 bytes Gigabit 230 bits Gigabyte 230 bytes Terabyte 240 bytes Petabyte 250 bytes Exabyte 260 bytes

Usage of Bits 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.

Data Rate and Storage Examples

• 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.

• 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 Techniques

• To reduce file size and transmission times, digital data can be compressed.
• Data compression refers to any technique that recodes the data in a file so that it contains fewer bits.
• Compression is commonly referred to as "zipping."

Lossless and Lossy Compression

• Compression techniques divided into two categories: lossless and lossy
• Lossless compression provides a way to compress data and reconstitute it into its original state; uncompressed data stays exactly the same as the original data

. Lossy compression throws away some of the original data during the compression process; uncompressed data is not exactly the same as the original

Compression Utilities and Tools

• 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.

Compressing Files on Mac and PC

FIGURE 1-8: COMPRESSING FILES Finder File Bot View @p Wrdew Het - 4 ters 1. Open Finder by selecting this icon. 2. Select one Detom or more files, right-click, ....... then select the Compress option. Compressing files using Finder on a Mac Cambridge Books Search Caror 2. Select one or more files, then right-click Donticadi Che Letie doe 3. Select these options to send the file to a compressed folder. 15, 100 KM Send Compressed (Posed: feier Donniced Descop (create shortcut 1. Open File Document Explorer by select- ing this icon. Mal recipient ID: e Compressing files using File Explorer on a PC

Extracting Compressed Files

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

Unzipping a Folder

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