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\title{Introduction to Computers}
\author{Ankur B. Sharma}
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\section{Introduction}
A computer is a device that can be instructed to carry out sequences of arithmetic or logical operations
automatically via computer programming. Modern computers have the ability to follow generalized
sets of operations, called programs. These programs enable computers to perform an extremely wide
range of tasks.
Conventionally, a modern computer consists of at least one processing element, typically a central
processing unit (CPU), and some form of memory. The processing element carries out arithmetic and
logical operations, and a sequencing and control unit can change the order of operations in response to
stored information. Peripheral devices include input devices (keyboards, mice, joystick, etc.), output
devices (monitor screens, printers, etc.), and input/output devices that perform both functions (e.g.,
the 2000s-era touchscreen). Peripheral devices allow information to be retrieved from an external
source and they enable the result of operations to be saved and retrieved.
\subsection{Concept of modern computers}
The principle of the modern computer was proposed by Alan Turing in his seminal 1936 paper,On
Computable Numbers, \cite{turing1937computable}. Turing proposed a simple device that he called Universal Computing machine" and that is now known as a universal Turing machine, as shown in Figure \ref{fig:mri2}. He proved that such a machine is capable of computing anything that is computable by executing instructions (program) stored on tape, allowing the machine to be programmable.
\subsubsection{Classification of Computers}
\begin{itemize}
\item Workstation
\item Personal Computer
\item Laptop
\item Mainframe Computer
\item Supercomputer
\end{itemize}
\begin{figure}[th]
\centering
\includegraphics[width=4in]{turing}
\caption{A representative Turing machine with a read/write head.}
\label{fig:mri2}
\end{figure}
\section{ Computer Hardware}
The core of the computer is the central processing unit (CPU). Some types of CPU are listed in
Table ~\ref{table:hard}
\begin{table} [ht]
\centering
\caption{Types of computer CPU}
\vspace{0.5 cm}
\label{table:hard}
\begin{tabular}{|c|c| } \hline
CPU Type & Micro architecture \\ \hline
4 bit & Intel 4004 \\ \hline
8 bit & Intel 8008 \\ \hline
16 bit & Zilog Z8000 \\ \hline
32 bit & Pentium \\ \hline
\end{tabular}
\end{table}
The time t taken to execute a program on a CPU is given by Equation~\ref{eq:t}.
\begin{equation}\label{eq:t}
t=IC\times CPI\times F
\end{equation}
IC = Instruction count
CPI = Average number of cycles required to execute instruction
F = Clock frequency.
\section{Applications of computer}\
Some applications of computer are listed below.
\begin{enumerate}
\item Banks and financial
\item Business
\item Communication
\item Education
\item Defense and military
\end{enumerate}
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