452 lines
14 KiB
TeX
452 lines
14 KiB
TeX
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\newcommand{\degree}{\ensuremath{^\circ}}
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%\documentclass[handout]{beamer}
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\documentclass[aspectratio=169,11pt]{beamer}
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% This file is a solution template for:
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% - Talk at a conference/colloquium.
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% - Talk length is about 20min.
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% - Style is ornate.
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% Copyright 2004 by Till Tantau <tantau@users.sourceforge.net>.
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%
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% In principle, this file can be redistributed and/or modified under
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% the terms of the GNU Public License, version 2.
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%
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% However, this file is supposed to be a template to be modified
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% for your own needs. For this reason, if you use this file as a
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% template and not specifically distribute it as part of a another
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% package/program, I grant the extra permission to freely copy and
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% modify this file as you see fit and even to delete this copyright
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% notice.
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\mode<presentation>
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{
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\usetheme{CambridgeUS}
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\usecolortheme{whale}
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%\setbeamercolor{titlelike}{parent=palette primary,fg=black}
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\setbeamercolor{frametitle}{use=block title,fg=black,bg=block title.bg!10!bg}
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% from beamercolorthemeorchid.sty to make it look more like warsaw
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\setbeamercolor{block title}{use=structure,fg=white,bg=structure.fg!75!black}
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\setbeamercolor{block title alerted}{use=alerted text,fg=white,bg=alerted text.fg!75!black}
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\setbeamercolor{block title example}{use=example text,fg=white,bg=example text.fg!75!black}
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\setbeamercolor{block body}{parent=normal text,use=block title,bg=block title.bg!10!bg}
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\setbeamercolor{block body example}{parent=normal text,use=block title example,bg=block title example.bg!10!bg}
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\setbeamertemplate{navigation symbols}{}
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% or ...
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%\setbeamercovered{transparent}
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% or whatever (possibly just delete it)
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}
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\mode<handout>{
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\usepackage{misc/handoutWithNotes}
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\pgfpagesuselayout{2 on 1 with notes landscape}[a4paper,border shrink=5mm]
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\usecolortheme{seahorse}
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}
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% ensure the page number is printed in front of the author name in the footer
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%\newcommand*\oldmacro{}
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%\let\oldmacro\insertshortauthor% save previous definition
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%\renewcommand*\insertshortauthor{%
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% \leftskip=.3cm% before the author could be a plus1fill ...
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% \insertframenumber\,/\,\inserttotalframenumber\hfill\oldmacro}
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\usepackage[english]{babel}
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\usepackage[utf8]{inputenc}
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\usepackage{times}
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\usepackage[T1]{fontenc}
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\usepackage{subfigure}
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\usepackage{hyperref}
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\usepackage{textcomp,listings}
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%\usepackage{german}
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\lstset{basicstyle=\scriptsize\ttfamily, upquote, tabsize=8}
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\title{DATEX-L, the German CSPDN}
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\subtitle{(Circuit Switched Public Data Network)}
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\author{Harald~Welte}
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\institute{Osmocom project}
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\date[January 2023]{RetroNetCall}
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% - Use the \inst command only if there are several affiliations.
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% - Keep it simple, no one is interested in your street address.
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% - Either use conference name or its abbreviation.
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% - Not really informative to the audience, more for people (including
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% yourself) who are reading the slides online
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%\subject{Having fun with DECT}
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% This is only inserted into the PDF information catalog. Can be left
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% out.
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% If you have a file called "university-logo-filename.xxx", where xxx
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% is a graphic format that can be processed by latex or pdflatex,
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% resp., then you can add a logo as follows:
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% \pgfdeclareimage[height=0.5cm]{university-logo}{university-logo-filename}
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% \logo{\pgfuseimage{university-logo}}
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% Delete this, if you do not want the table of contents to pop up at
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% the beginning of each subsection:
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%\AtBeginSubsection[]
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%{
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% \begin{frame}<beamer>{Outline}
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% \tableofcontents[currentsection,currentsubsection]
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% \end{frame}
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%}
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% If you wish to uncover everything in a step-wise fashion, uncomment
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% the following command:
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%\beamerdefaultoverlayspecification{<+->}
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\begin{document}
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\begin{frame}
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\titlepage
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\end{frame}
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% Structuring a talk is a difficult task and the following structure
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% may not be suitable. Here are some rules that apply for this
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% solution:
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% - Exactly two or three sections (other than the summary).
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% - At *most* three subsections per section.
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% - Talk about 30s to 2min per frame. So there should be between about
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% 15 and 30 frames, all told.
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% - A conference audience is likely to know very little of what you
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% are going to talk about. So *simplify*!
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% - In a 20min talk, getting the main ideas across is hard
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% enough. Leave out details, even if it means being less precise than
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% you think necessary.
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% - If you omit details that are vital to the proof/implementation,
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% just say so once. Everybody will be happy with that.
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%\include{part-introduction}
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%\part{Java SIM}
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\begin{frame}{Disclaimer}
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\begin{itemize}
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\item I never used Datex-L back in the day
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\item All information presented is from historical books / specs / articles
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\item My understanding might be incorrect; Corrections welcome!
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\end{itemize}
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\end{frame}
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\section{Cicruit Switched Packet Data Networks}
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\begin{frame}{CSPDN? WTF?}
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\begin{itemize}
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\item Circuit Switched
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\begin{itemize}
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\item dedicated circuits, dialled and released
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\item just like the good old telephony (PSTN) network
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\end{itemize}
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\item Public Data Network
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\begin{itemize}
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\item available to the general public (like PSTN)
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\item used for data, not speech (unlike PSTN)
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\end{itemize}
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\end{itemize}
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CSPDNs were {\bf separate} networks, independent of telephony networks
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\end{frame}
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\begin{frame}{Before CSPDNs}
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\begin{itemize}
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\item Public switched Telephony network (PSTN)
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\begin{itemize}
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\item analog 3.4 kHz circuit, end-to-end
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\item initially manually switched, later electromechanical switching
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\end{itemize}
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\item Public switched Telex network (Telex)
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\begin{itemize}
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\item 50 bit per second, asynchronous, analog
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\item initially manually switched, later electromechanical switching
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\end{itemize}
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\item direct point-to-point links (Standleitung, HfD)
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\begin{itemize}
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\item no switching involved; dedicated permanent leased circuit
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\item HfD: {\em Hauptanschluß für Direktruf}: leased line with DCE/modem provided by operator
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\item {\em Überlassung posteigener Stromwege}: just the bare coper, no DCE/modem provided by operator
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\end{itemize}
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\end{itemize}
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\end{frame}
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\begin{frame}{Some basic terminology}
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\begin{description}
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\item[DBP] Deutsche Bundespost; German postal services
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\item[CSPDN] Circuit Switched Packet Data Network; describes abstract concept (CCITT/ITU-T)
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\item[DATEX] DATa EXchange; Data services provided by Deutsche Bundespost
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\item[DATEX-L] DATa EXchange Leitungsorientiert; CSPDN by Deutsche Bundespost
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\item[DATEX-P] DATa EXchange Paketorientiert; PSPDN by Deutsche Bundespost (off-topic here)
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\item[IDN] Integriertes Text- und Datennetz; German network used to provide Telex, Gentex and Datex services
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\item[EDS] Elektronisches Datenvermittlungs-System; Switching technology used to implement IDN
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\end{description}
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\end{frame}
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\begin{frame}{Different Services/Networks in 1980}
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\begin{figure}[h]
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\centering
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\includegraphics[width=99mm]{dbp_netze.jpg}
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\end{figure}
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\end{frame}
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\section{DATEX-L}
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\begin{frame}{Why DATEX-L or a CSPDN?}
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Why have a separate data network, indepedent of the telephony network?
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\begin{itemize}
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\item it's difficult to transmit digital data over hundreds or even thousands of kilometers of analog telephone lines
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\item Modems for the PSTN were very expensive and slow in the 60s and 70s
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\item Very long connection establishment time (pulse dialing, electromechanics)
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\item a network with digital switching enables {\em re-generating} the signal hop-by-hop
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\end{itemize}
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\begin{figure}[h]
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\centering
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\includegraphics[width=99mm]{abschnittsweise_uebertragung.jpg}
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\end{figure}
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\end{frame}
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\begin{frame}{DATEX-L Network Architecture}
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\begin{figure}[h]
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\centering
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\includegraphics[width=99mm]{datex-l-arch.png}
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\end{figure}
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\end{frame}
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\begin{frame}{DATEX-L points of presence}
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\parbox{.45\textwidth}{
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\includegraphics[width=50mm]{standorte.jpg}
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}\hfill\parbox{.50\textwidth}{
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\begin{itemize}
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\item 18 Datex-L Switches (DVST) all over Germany
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\item 18 switch co-located mulitplexers (DUST-D)
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\item 400 remote Multiplexers (DUST-U)
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\end{itemize}
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}
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\end{frame}
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\begin{frame}{DATEX-L Terminology}
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\begin{description}
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\item[DVST] {\em Datenvermittlungsstelle}; Data Switch
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\item[DUST-D] {\em Datenumsetzerstelle am Standort der Datenvermittlungsstelle}; subscriber line
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multiplexers co-located with DVST
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\item[DUST-U] {\em Datenumsetzerstelle der unteren Netzebene}; subscriber line multiplexers located
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remote from switches; typically in PSTN central offices that had no DVST
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\item [DEE] {\em Datenendeinrichtung}; DTE (Data Terminal Equipment)
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\item [DÜE] {\em Datenübertragungseinrichtung}; DCE (Data Communications Equipment)
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\item [UEB] {\em Übertragungseinheiten}; line transmission interface at DUST
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\item [DFG] {\em Datenfernschaltgerät}; Siemens implementation of DÜE (DCE)
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\end{description}
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\end{frame}
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\begin{frame}{DEE-DÜE (DTE-DCE) Interfaces}
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\begin{itemize}
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\item interface to network was not the subscriber line, but a serial port
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\item DATEX-L was a synchronous network, so synchronous interfaces preferred
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\begin{itemize}
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\item sync interfaces: X.20 (300 bps) or X.21 (2400/4800/9600 bps)
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\item async interfaces: X.20bis (300 bps), X.21bis (2400/4800/9600 bps)
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\end{itemize}
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\item asynchronous interfaces were more expensive, as
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\begin{itemize}
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\item additional circuitry needed in DEE (DCE)
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\item lower net throughput due to bits wasted for start/stop bits
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\end{itemize}
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\end{itemize}
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\end{frame}
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\begin{frame}{DATEX-L Services}
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\centering
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\begin{tabular}{| l | l | l | l |}
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\hline
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Name & bps & Inaugurated & Subscriber Interface\\
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\hline
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DATEX-L200 & 50-200 & 1967 & X.20bis \\
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DATEX-L300 & 300 & 1976 & X.20 or X.20bis \\
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DATEX-L2400 & 2400 & 1978 & X.21 or X.21bis \\
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DATEX-L4800 & 4800 & 1979 & X.21 or X.21bis \\
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DATEX-L9600 & 9600 & 1970 & X.21 or X.21bis \\
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\hline
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\end{tabular}
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\end{frame}
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\begin{frame}{DATEX-L DÜE/DCE/DFG: DFG 300 / DFG 2400}
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\parbox{.50\textwidth}{
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\includegraphics[width=60mm]{dfg300-1.jpg}
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}\hfill\parbox{.50\textwidth}{
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\includegraphics[width=60mm]{dfg2400.jpg}
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}
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\end{frame}
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\begin{frame}{DATEX-L DÜE/DCE/DFG: DFG 9600UE-1 / DFG9600UE-2}
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\parbox{.50\textwidth}{
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\includegraphics[width=60mm]{dfg9600ue1.jpg}
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}\hfill\parbox{.50\textwidth}{
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\includegraphics[width=70mm]{dfg9600ue2.jpg}
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}
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\end{frame}
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\begin{frame}{Subcriber Line in DATEX-L}
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\begin{itemize}
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\item remember: subscriber line was {\bf not} the public interface
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\item depending on distance, different technologies used
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\item predominantly pseudo-ternary coded base band transmission (UEB)
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\item occasionally (long distance to DUST) modem 2DPSK/4DPSK (UEM)
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\item 2-bit {\em envelope} added to every 8 user bits
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\begin{itemize}
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\item 1 bit for synchronization purpose
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\item 1 bit to differentiate user payload from signaling traffic
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\item result: data rate on subscriber line 25\% higher than at user interface
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\end{itemize}
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\end{itemize}
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\end{frame}
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\begin{frame}{DATEX-L Charges: Monthly subscription}
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\centering
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\begin{tabular}{| l | l | l |}
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\hline
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Service & Interface & Fee per month (DM)\\
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\hline
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DATEX-L300 & X.20 & 100\\
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DATEX-L300 & X.20bis & 120\\
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DATEX-L2400 & X.21 & 170\\
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DATEX-L2400 & X.21bis & 200\\
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DATEX-L4800 & X.21 & 270\\
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DATEX-L4800 & X.21bis & 300\\
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DATEX-L9600 & X.21 & 370\\
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DATEX-L9600 & X.21bis & 400\\
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\hline
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\end{tabular}
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\end{frame}
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\begin{frame}{DATEX-L Charges: Per connection/duration}
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\parbox{.75\textwidth}{
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\centering
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\includegraphics[width=90mm]{gebuehrenstruktur.jpg}
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}\hfill\parbox{.25\textwidth}{
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\begin{itemize}
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\item Pfg = Pfennig (1/100 DM)
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\item fixed 5 Pfg for connection setup
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\item distance and speed dependent charges for ever 0.1 s duration
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\end{itemize}
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}
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\end{frame}
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\begin{frame}{DATEX-L Charges: What did it cost per MB?}
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Inflation-corrected (1980->2022) charges in EUR per Megabyte:
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\centering
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\begin{tabular}{| l | r | r | r |}
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\hline
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Service & > 50km (day) & > 50km (night I) & > 50km (night II)\\
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\hline
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DATEX-L300 & 50.29 & 25.79 & 25.79\\
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DATEX-L2400 & 7.52 & 3.87 & 1.93\\
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DATEX-L4800 & 6.28 & 3.22 & 1.61\\
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DATEX-L9600 & 5.35 & 2.74 & 1.36\\
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\hline
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\end{tabular}
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\end{frame}
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\begin{frame}{DATEX-L International CSPDN interconnect}
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\begin{itemize}
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\item 1970: France
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\item 1973: Belgium
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\item 1981: Denmark, Finland, Norway, Sweden (NPDN)
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\end{itemize}
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\end{frame}
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%\begin{frame}{}
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\begin{frame}{Datex-L DVST + DUST-D Floorplan}
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\begin{figure}[h]
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\centering
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\includegraphics[width=140mm]{raumanordnung_dvst_dust.jpg}
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\end{figure}
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\end{frame}
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\begin{frame}{Datex-L DVST + DUST Technical data}
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\begin{tabular}{l | l}
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Maximum capacity & 16384 connections \\
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Maximum subscriber lines & 10880 .. 11500 \\
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Maximum memory capacity & 1 MByte (core memory)\\
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Maximum call setup rate & 30 per second / 60 per second\\
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Power consumption & 80 kW @ 60 VDC + 15kW @ 220 VAC + air conditioning\\
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net floor space (just racks) & 200 m\textsuperscript{2}\\
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gross floor space & 1200 m\textsuperscript{2}
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\end{tabular}
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\end{frame}
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\section{EDS}
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\begin{frame}{EDS History}
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\begin{itemize}
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\item need for higher bit rate (than 50 bps Telex) wide area data transmission
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\item conceptual development from 1965 onwards triggered by DBP
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\item cooperation between Siemens and SEL (Standard Elektronik Lorenz)
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\item production deployments as IDN at Deutsche Bundespost from 1975 onwards
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\item more than 60\% of all Telex and Datex subscribers migrated to EDS in 1978
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\item de-commissioned in 1996 when Datex-L was switched off
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\end{itemize}
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\end{frame}
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\begin{frame}{EDS System Structure}
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\begin{figure}[h]
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\centering
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\includegraphics[width=71mm]{eds_struktur.jpg}
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\end{figure}
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\end{frame}
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\begin{frame}{DUST using Siemens ZD1000}
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\begin{figure}[h]
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\centering
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\includegraphics[width=97mm]{siemens_zd1000.jpg}
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\end{figure}
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\end{frame}
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\begin{frame}{DUST using Siemens ZD1000}
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\begin{figure}[h]
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\centering
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\includegraphics[width=127mm]{siemens_zd1000se.jpg}
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\end{figure}
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\end{frame}
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\begin{frame}{DVST Hard Disk Storage}
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\begin{figure}[h]
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\centering
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\includegraphics[width=90mm]{plattenspeicher.jpg}
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\end{figure}
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\end{frame}
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\begin{frame}{The End}
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EOF
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\end{frame}
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\end{document}
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