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% Document Info
\author{AlexHoratio (Horatio)}
\pdfinfo{
  /Title (wjec-a2-computing-unit-4-2.pdf)
  /Creator (Cheatography)
  /Author (AlexHoratio (Horatio))
  /Subject (WJEC A2 Computing Unit 4.2 Cheat Sheet)
}

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\noindent
\begin{multicols}{3}
\begin{tabulary}{5.8cm}{C}
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    \vspace{-7pt}
    {\parbox{\dimexpr\textwidth-2\fboxsep\relax}{\noindent
        \hspace*{-6pt}\includegraphics[width=5.8cm]{/web/www.cheatography.com/public/images/cheatography_logo.pdf}}
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\begin{tabulary}{11cm}{L}
    \vspace{-2pt}\large{\bf{\textcolor{DarkBackground}{\textrm{WJEC A2 Computing Unit 4.2 Cheat Sheet}}}} \\
    \normalsize{by \textcolor{DarkBackground}{AlexHoratio (Horatio)} via \textcolor{DarkBackground}{\uline{cheatography.com/21127/cs/16078/}}}
\end{tabulary}
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\noindent
\begin{multicols}{3}
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  \mymulticolumn{2}{p{5.377cm}}{\bf\textcolor{white}{Cheatographer}}  \\
  \vspace{-2pt}AlexHoratio (Horatio) \\
  \uline{cheatography.com/horatio} \\
        \uline{\seqsplit{alexhoratiogamedev}.blogspot.com}
  \end{tabulary}
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  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Cheat Sheet}}  \\
   \vspace{-2pt}Not Yet Published.\\
   Updated 12th June, 2018.\\
   Page {\thepage} of \pageref{LastPage}.
\end{tabulary}
\vfill
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  \vspace{-5pt}
  %\includegraphics[width=48px,height=48px]{dave.jpeg}
  Measure your website readability!\\
  www.readability-score.com
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\end{multicols}}




\begin{document}
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% www.emerson.emory.edu/services/latex/latex_169.html
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\begin{multicols*}{3}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Data Transmission}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{{\bf{Parallel Transmission}}} \tn 
\mymulticolumn{1}{x{5.377cm}}{\hspace*{6 px}\rule{2px}{6px}\hspace*{6 px}This is {\bf{multiple wires}} sending a number of bits at the same time. \{\{nl\}\}This is used in buses in the CPU but can only be used for {\bf{short distances}} due to interference. \{\{nl\}\}This is much {\bf{faster}} than serial transmssion, but may have {\bf{synchronization problems}}.} \tn 
% Row Count 7 (+ 7)
% Row 1
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\mymulticolumn{1}{x{5.377cm}}{{\bf{Serial Transmission}}} \tn 
\mymulticolumn{1}{x{5.377cm}}{\hspace*{6 px}\rule{2px}{6px}\hspace*{6 px}Bits are sent {\bf{serially}} across a single wire. \{\{nl\}\} This is used for {\bf{longer distances}} and is frequently used in computer cables. \{\{nl\}\} There are three types of serial transmission: \{\{nl\}\} {\bf{1. Simplex}} - Transmission in one direction only. \{\{nl\}\} {\bf{2. Half-Duplex}} - Transmission in both directions, but only one at a time. \{\{nl\}\} {\bf{3. Full-Duplex}} - Transmission in both directions simultaneously.} \tn 
% Row Count 17 (+ 10)
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\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Bandwidth}}  \tn
% Row 0
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\mymulticolumn{1}{x{5.377cm}}{Bandwidth is the amount of data that can be transmitted at a time along a {\bf{single communication channel}}.} \tn 
% Row Count 3 (+ 3)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{This is related to the {\bf{range of frequencies}} available on the carrier wave.} \tn 
% Row Count 5 (+ 2)
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\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Multiplexing}}  \tn
% Row 0
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\mymulticolumn{1}{x{5.377cm}}{{\bf{Multiplexing}} involves combining more than one signal through a single communications channel.} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{When the signal reaches its destination, it has to be {\bf{demultiplexed}} or {\bf{demuxed}}. This involves decoding the multiplexed signal to extract the original data.} \tn 
% Row Count 6 (+ 4)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{{\bf{Inverse multiplexing}} breaks one data stream into several data streams to be sent seperately over multiple chnanels, where it can be re-assembled at the destination.} \tn 
% Row Count 10 (+ 4)
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\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Bit Rate}}  \tn
% Row 0
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\mymulticolumn{1}{x{5.377cm}}{The {\bf{speed}} at which a transmission is taking place. This is proportional to {\bf{bandwidth}}, since bandwidth can determine how many bits can be transmitted at a time.} \tn 
% Row Count 4 (+ 4)
% Row 1
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\mymulticolumn{1}{x{5.377cm}}{This is measured in {\bf{bits per second}} or {\bf{bps}}.} \tn 
% Row Count 6 (+ 2)
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\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Baud Rate}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{One {\bf{baud}} represents one electronic state change per second.} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{In a system where one bit is sent per each state change, {\bf{one baud}} would equate to {\bf{one bit per second}}.} \tn 
% Row Count 5 (+ 3)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{However, it is possible to store multiple voltages as representing {\bf{combinations of bits}}. \{\{nl\}\}For example, {\bf{1Hz}} might represent "{\bf{1010}}", {\bf{2Hz}} might represent "{\bf{1111}}", etc.\{\{nl\}\} This way the number of state changes can remain constant while bits per second increases.} \tn 
% Row Count 11 (+ 6)
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Types of Switching}}  \tn
% Row 0
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\mymulticolumn{1}{x{5.377cm}}{{\bf{Circuit Switching}}} \tn 
\mymulticolumn{1}{x{5.377cm}}{\hspace*{6 px}\rule{2px}{6px}\hspace*{6 px}This is when a specific route of switches is determined and data is sent only down that specific path. This path is maintained for the duration of the transmission.} \tn 
% Row Count 5 (+ 5)
% Row 1
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\mymulticolumn{1}{x{5.377cm}}{{\bf{Packet Switching}}} \tn 
\mymulticolumn{1}{x{5.377cm}}{\hspace*{6 px}\rule{2px}{6px}\hspace*{6 px}Data is split into {\bf{packets}}. Each packet contains {\bf{data}}, the {\bf{source address}}, the {\bf{destination address}}, and a {\bf{checksum}}. Each packet may take a different route around the network.\{\{nl\}\} This means that if one computer fails, the message can still be sent. Also, it is more difficult to intercept.} \tn 
% Row Count 13 (+ 8)
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\par\addvspace{1.3em}


% That's all folks
\end{multicols*}

\end{document}