diff options
Diffstat (limited to 'talermerchantdemos/blog/articles/scrap1_46.html')
| -rw-r--r-- | talermerchantdemos/blog/articles/scrap1_46.html | 292 |
1 files changed, 0 insertions, 292 deletions
diff --git a/talermerchantdemos/blog/articles/scrap1_46.html b/talermerchantdemos/blog/articles/scrap1_46.html deleted file mode 100644 index 914a985..0000000 --- a/talermerchantdemos/blog/articles/scrap1_46.html +++ /dev/null @@ -1,292 +0,0 @@ -<!-- This is the second edition of Free Software, Free Society: Selected Essays of Richard M. Stallman. - -Free Software Foundation - -51 Franklin Street, Fifth Floor - -Boston, MA 02110-1335 -Copyright C 2002, 2010 Free Software Foundation, Inc. -Verbatim copying and distribution of this entire book are permitted -worldwide, without royalty, in any medium, provided this notice is -preserved. Permission is granted to copy and distribute translations -of this book from the original English into another language provided -the translation has been approved by the Free Software Foundation and -the copyright notice and this permission notice are preserved on all -copies. - -ISBN 978-0-9831592-0-9 -Cover design by Rob Myers. - -Cover photograph by Peter Hinely. - --> - - - <a name="Freedom-or-Power_003f"> - </a> - <a name="Appendix-A_003a-A-Note-on-Software"> - </a> - <h1 class="unnumbered"> - <span class="roman"> - Appendix A: A Note on Software - </span> - </h1> - <p> - Written by Richard E. Buckman and Joshua Gay. - <br/> - </p> - <p> - This section is intended for people who have little or no knowledge of -the technical aspects of computer science. It is not necessary to read -this section to understand the essays and speeches presented in this -book; however, it may be helpful to those readers not familiar with -some of the jargon that comes with programming and computer science. - </p> - <p> - A computer - <em> - programmer - </em> - writes software, or computer programs. A -program is more or less a recipe with - <em> - commands - </em> - to tell the -computer what to do in order to carry out certain tasks. You are more -than likely familiar with many different programs: your Web browser, -your word processor, your email client, and the like. - </p> - <p> - A program usually starts out as - <em> - source code - </em> - . This higher-level -set of commands is written in a - <em> - programming language - </em> - such as C -or Java. After that, a tool known as a - <em> - compiler - </em> - translates this -to a lower-level language known as - <em> - assembly language - </em> - . Another -tool known as an - <em> - assembler - </em> - breaks the assembly code down to the -final stage of - <em> - machine language - </em> - —the lowest level—which the -computer understands - <em> - natively - </em> - . - </p> - <img alt="code" src="/essay/Appendix_A:_A_Note_on_Software/data/code.jpg"> - <p> - For example, consider the -“hello world” program, a common first program for people learning C, -which (when compiled and executed) prints “Hello World!” on the screen. - <a href="#FOOT54" name="DOCF54"> - (54) - </a> - </p> - <table> - <tr> - <td> - </td> - <td> - <pre class="smallexample">int main(){ - printf(''Hello World!''); - return 0; -} -</pre> - </td> - </tr> - </table> - <p> - In the Java programming language the same program would -be written like this: - </p> - <table> - <tr> - <td> - </td> - <td> - <pre class="smallexample">public class hello { - public static void main(String args[]) { - System.out.println(''Hello World!''); - } -} -</pre> - </td> - </tr> - </table> - <p> - However, in machine language, a small section of it may look similar to -this: - </p> - <table> - <tr> - <td> - </td> - <td> - <pre class="smallexample">1100011110111010100101001001001010101110 -0110101010011000001111001011010101111101 -0100111111111110010110110000000010100100 -0100100001100101011011000110110001101111 -0010000001010111011011110111001001101100 -0110010000100001010000100110111101101111 -</pre> - </td> - </tr> - </table> - <p> - The above form of machine language is the most basic representation -known as binary. All data in computers is made up of a series of -0-or-1 values, but a person would have much difficulty understanding -the data. To make a simple change to the binary, one would have to -have an intimate knowledge of how a particular computer interprets the -machine language. This could be feasible for small programs like the -above examples, but any interesting program would involve an -exhausting effort to make simple changes. - </p> - <p> - As an example, imagine that we wanted to make a change to our “Hello -World” program written in C so that instead of printing “Hello World” -in English it prints it in French. The change would be simple; here is -the new program: - </p> - <table> - <tr> - <td> - </td> - <td> - <pre class="smallexample">int main() { - printf(''Bonjour, monde!''); - return 0; -} -</pre> - </td> - </tr> - </table> - <p> - It is safe to say that one can easily infer how to change the program -written in the Java programming language in the same way. However, -even many programmers would not know where to begin if they wanted to -change the binary representation. When we say “source code,” we do -not mean machine language that only computers can understand—we are -speaking of higher-level languages such as C and Java. A few other -popular programming languages are C++, Perl, and Python. Some are -harder than others to understand and program in, but they are all much -easier to work with compared to the intricate machine language -they get turned into after the programs are compiled and assembled. - </p> - <p> - Another important concept is understanding what an - <em> - operating -system - </em> - is. An operating system is the software that handles input and -output, memory allocation, and task scheduling. Generally one -considers common or useful programs such as the - <em> - Graphical User -Interface - </em> - (GUI) to be a part of the operating system. The GNU/Linux -operating system contains a both GNU and non-GNU software, and a - <em> - kernel - </em> - called - <em> - Linux - </em> - . The kernel handles low-level tasks -that applications depend upon such as input/output and task -scheduling. The GNU software comprises much of the rest of the -operating system, including GCC, a general-purpose compiler for many -languages; GNU Emacs, an extensible text editor with many, many -features; GNOME, the GNU desktop; GNU libc, a library that all -programs other than the kernel must use in order to communicate with -the kernel; and Bash, the GNU command interpreter that reads your -command lines. Many of these programs were pioneered by Richard -Stallman early on in the GNU Project and come with any modern -GNU/Linux operating system. - </p> - <p> - It is important to understand that even if - <em> - you - </em> - cannot -change the source code for a given program, or directly use all these -tools, it is relatively easy to find someone who can. Therefore, by -having the source code to a program you are usually given the power to -change, fix, customize, and learn about a program—this is a power that -you do not have if you are not given the source code. Source -code is one of the requirements that makes a piece of software - <em> - free - </em> - . The other requirements will be found along with the -philosophy and ideas behind them in this collection. - </p> - <div class="footnote"> - <hr> - <h3> - Footnotes - </h3> - <h3> - <a href="#DOCF54" name="FOOT54"> - (54) - </a> - </h3> - <p> - In other programming languages, such as -Scheme, the - <em> - Hello World - </em> - program is usually not your first program. -In Scheme you often start with a program like this: - </p> - <table> - <tr> - <td> - </td> - <td> - <pre class="smallexample">(define (factorial n) - (if (= n 0) - 1 - (* n (factorial (- n 1))))) -</pre> - </td> - </tr> - </table> - <p> - This computes the factorial of a number; that is, running - <code> - (factorial 5) - </code> - would output 120, which is computed by doing -5 * 4 * 3 * 2 * 1 * 1. - </p> - </hr> - </div> - <hr size="6"/> - </img> - |