Difference between revisions of "Tutorial4: Data Representation / Numbering Conversion / File Permissions"
(→Decimal / Binary / Octal / Hexadecimal Numbering Systems) 
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''Octal / Hexadecimal Numbers''  ''Octal / Hexadecimal Numbers''  
−  <table><tr><td>[[Image:octalnumber1.pngthumbright200pxThe '''octal''' numbering system .]]</td><td>[[Image:hexnumber1.pngthumbright200pxThe '''hexadecimal''' numbering system .]]</td></tr></table>  +  <table align="right"><tr><td>[[Image:octalnumber1.pngthumbright200pxThe '''octal''' numbering system .]]</td><td>[[Image:hexnumber1.pngthumbright200pxThe '''hexadecimal''' numbering system .]]</td></tr></table> 
The '''octal''' and ''hexadecimal'' numbering systems are represented by values of 0  7 and 0  F respectively. For hexadecimal numbers, values for 10 to 15 (which can only be represented by a single digit) use letters a to f respectively.  The '''octal''' and ''hexadecimal'' numbering systems are represented by values of 0  7 and 0  F respectively. For hexadecimal numbers, values for 10 to 15 (which can only be represented by a single digit) use letters a to f respectively.  
Revision as of 16:56, 17 January 2020
Contents
Data Representation / Numbering Conversion / File Permissions
Main Objectives of this Practice Tutorial
 Understand the importance of how computers store data (i.e. data representation)
 Understand the purpose of decimal, binary, octal and hexadecimal numbers
 Perform various numbering conversions between the decimal, binary, octal and hexadecimal numbering systems
by hand without the use of a computer or calculator
 Perform various numbering conversions between the decimal, binary, octal and hexadecimal numbering systems
 Identify which numbering system conversion method to use when required to perform a numbering conversion
 Understand directory and regular file permissions
 Learn how to set directory and regular file permissions with the chmod command (symbolic and octal methods)
 Learn how to use the umask command to have permissions for directories and files automatically set upon their creation
 Learn how to use the umask command to have permissions for directories and files automatically set upon their creation
Tutorial Reference Material
Course Notes 
Numbering Conversion / File Permissions Reference 
YouTube Videos  
Course Notes:

Data Representation
Numbering Conversion

File Permissions  Instructional Videos:

Why Study Data Representation?
Data (treated as singular, plural, or as a mass noun) is any sequence of one or more symbols given meaning by specific act(s) of interpretation.
Digital data is data that is represented using the binary number system of ones (1) and zeros (0), as opposed to analog representation.
Reference: https://en.wikipedia.org/wiki/Data_(computing)
Therefore, computers process and store information in a binary number system consisting of 0s and 1s. For many aspects of programming and networking, the details of data representation must be understood.
Reasons to Understand Data Representation:
 C Programming: Sending information over networks, files
 Web Development: Setting color codes for webpage background or text
 Allowing or Limiting Unix / Linux File Access: Setting permissions for files and directories
In terms of this course, we will learn how a simple decimal number (integer) is stored into the computer system as a binary number. We will also learn other numbering systems (octal and hexadecimal) that can be used as a "shortcut" to represent binary numbers.
Decimal / Binary / Octal / Hexadecimal Numbering Systems
Decimal Numbers
The decimal numbering system is a numbering system where each digit can be represented by numbers 0  9. The reason for this system may be attributed to the fact that humans were used to counting on their fingers and thumbs.
The numbering system is based on sums of the power of 10.
According to the diagram to the right, each digit moving to the left of units value is the placeholder multiplied to the power of ten. Units are ten to the power of zero (which is 1), tens are ten to the power of one, etc.
Binary Numbers
The binary numbering system is a numbering system where each digit can be represented by numbers 0 or 1. Digital computers have datapaths that can represent those 0s and 1s based on voltage levels.
The numbering system is based on sums of the power of 2.
According to the diagram to the right, each digit moving to the left of units value is the placeholder multiplied to the power of two. Units are ten to the power of zero (which is 1), then two to the power of one (which is 2), etc.
Octal / Hexadecimal Numbers
The octal and hexadecimal numbering systems are represented by values of 0  7 and 0  F respectively. For hexadecimal numbers, values for 10 to 15 (which can only be represented by a single digit) use letters a to f respectively.
The numbering system is based on sums of the power of 2.
According to the diagram to the right, each digit moving to the left of units value is the placeholder multiplied to the power of two. Units are ten to the power of zero (which is 1), then two to the power of one (which is 2), etc.
Numbering Conversions
x
File Permissions
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INVESTIGATION 1: NUMBERING CONVERSIONS
x.
INVESTIGATION 2: FILE PERMISSIONS
x.