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\author{Piyush P Kurur\\
  Office no: 224\\
  Dept. of Comp. Sci. and Engg.\\
  IIT Kanpur}

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\date{July 29, 2009}
\begin{document}
\begin{frame}

\frametitle{Summary of last class}

\begin{definition}
  Algorithms are finite sequence of \emph{basic instructions} to carry
  out a particular task. The actual instructions depends on the model
  of computation that we are talking about.
\end{definition}

\pause
\begin{block}{Examples}
  \begin{itemize}
  \item Cooking recipies,
  \item Operational manual of a music system,
  \item Navigational directions,
  \item And of course computer programs.
  \end{itemize}
\end{block}

\end{frame}

\begin{frame}

\frametitle{von Neumann architecture}
\begin{multicols}{2}
\input{figures/vonNeumann.tex}
\newpage
\pause
\begin{block}{Basic instructions}
  
\begin{itemize}
  \pause
\item Read/write data from memory/IO devices,
  \pause
\item Perform arithmetic logical operations on data,
  \pause
\item Read instructions from memory and interpret them.
  \pause
\item Proceed according to the instructions.
  \pause
\end{itemize}

\end{block}
\end{multicols}

\end{frame}

\begin{frame}
  \frametitle{Programming language}
  
  One can think of a programming language as
  a way of expressing algorithms, or as a model
  of computation

  \pause
  \begin{block}{Kinds of programming languages}
    \begin{itemize}
      \pause
    \item Low level languages; eg Assembly/Machine language
      \pause
    \item High level language; eg Pascal, Python etc.
      \pause
    \item Middle level language; eg C
    \end{itemize}
  \end{block}
  
  \pause
  The higher the level of language the closer to human beings.  The
  lower level language is closer to the machine.

\end{frame}

\begin{frame}
  \begin{block}{Why high level language?}
    \pause
    Look at computers from Programmers perspective.
    \begin{itemize}
      \pause
    \item Easier to write programs in.
      \pause
    \item Being generic, it is more portable.
    \end{itemize}
  \end{block}
  \begin{block}{Why then low level language?}
    \pause
    Easier to realise on hardware.
    
  \end{block}
  
\end{frame}




\begin{frame}

  \begin{code}
    #include<stdio.h>
    
    int main()
    {
      int n;
      int sum=0;
      scanf("%d",&n);

      while(n > 0)
      {
        sum = sum + n;
        n   = n - 1;
      }
      
      printf("%d",sum);
    }
\end{code}

\end{frame}

\begin{frame}
  \frametitle{Assemblers, Compilers, Interpreters}
 
  \begin{itemize}
    \pause
  \item Assemblers are the most basic translators.
    On Unix system the assembler is called |as|.
    \pause
  \item High level language requires compilers. C, Pascal
    \pause
  \item Some languages are interpreted. eg Python, lisp etc
  \end{itemize}
\end{frame}



\begin{frame}
  \frametitle{Other classification of programming languages}

  \begin{itemize}
  \item Imperative programming language; eg C, Pascal, Python
    Glorified von Neumann architecture.
  \item Functional programming language; eg Haskell
    No states, only functions
  \item Object oriented languages; eg Smaltalk, Simula etc.
    Objects and messages to objects
  \item Logic based language; prolog
    Logic based techniques, Resolution.
  \item Scripting languages
  \end{itemize}
\end{frame}

\begin{frame}
  \frametitle{What to expect in this course}

  We will study one imperative language C.

  and a scripting language the shell.

\end{frame}
\end{document}