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  Looking at the green characters displayed on the black screen, Lin Hong was no longer as bewildered as before.

  He now knows that what is displayed at the top is the name and version number of the operating system inside this computer.

  The Apple II was equipped with the latest version of the Apple DOS operating system, v3.3. Prior to this, there were versions 3.1 and 3.2, but these earlier versions had fewer features and were based on cassette tape storage devices. This version was also the most famous and widely used version of Apple DOS. Later Apple computers used the ProDOS operating system, which was specifically designed by Microsoft.

  Apple DOS is the first disk-based operating system for Apple computers, and naturally, the genius computer engineer Wozniak was involved in writing a large part of the code.

  Looking at the blinking green "[" symbol on the monitor, Lin Hong stretched out two index fingers and lowered his head to look at the keys on the keyboard. On the keyboard, there were printed corresponding letters. He slowly and laboriously pressed a few keys, and the word "catalog" appeared slowly and laboriously on the monitor.

  Lin Hong was puzzled as to why the keyboard layout had the letters arranged in such a way that "a" and "b" were so far apart.

  It wasn't until much later that he learned this keyboard layout was called the "QWERTY keyboard", which had been invented in the mid-19th century, originally for mechanical typewriters.

  The reason for this layout is due to the structure of mechanical typewriters, whose lead typebars' structure determined that when two adjacent keys were pressed simultaneously they would jam, but more distant keys would not have this problem. This layout was retained with the appearance of computers later on.

  After laboriously typing in this command, Lin Hong pressed the Enter key, and finally there was a change on the display screen. A long list immediately appeared, which was a directory display command, and these contents were exactly what was installed inside the disk.

  Seeing this result, Lin Hong's face showed a happy smile.

  This was his first computer operation command input, although the process was simple, but still made him feel very excited and thrilled.

  Watching this computer under its own operation and then starting to have a reaction, the sense of conquest that everything is under one's control is difficult to describe in words.

  This is probably why boys like all sorts of toys and machines.

  Next, Lin Hong began to try out each command one by one according to the content described in the reference book, and then observed the results. Looking at the various information flashing on the display, he felt a sense of accomplishment that could not be expressed in words.

  The meaning of "dir" is "directory", which means displaying the file directory inside the disk. There is also "intbasic", which means entering the integer basic language programming state. After entering this command, you can start writing code for programming.

  So-called system commands are actually small pieces of software. Operating systems usually come with some common software, binding them to the system, which becomes a system command.

  If you are not satisfied with the commands in the system and think that you can implement the same functionality in a better way, you can also write your own small tool to replace the original software.

  After playing with system commands for a while, Lin Hong started hands-on programming practice in BASIC language.

  The language of computer programming, as the name suggests, is a language between humans and computers. It was invented to be easily understood by humans. When computers were first invented, those pioneers directly used machine language to operate on computers.

  Programming languages can be roughly divided into low-level languages and high-level languages. Low-level languages include machine language and assembly language.

  What is meant by "low-level" does not refer to the fact that the language function is not strong, but rather it is distinguished from the ease of mastery for beginners. In fact, low-level languages have more powerful functions and the programs written are more efficient.

  High-level language is a later language, the purpose is to make people better understand, and it's very close to the text that people usually write. The "ion_code" is an abbreviation, which means "novice-oriented symbolic instruction code" in Chinese.

  This language was created by two American computer scientists specifically for college students on campus, with the goal of making it easy for college students to use computers. Although the initial BASIC had only a few dozen statements, because BASIC was relatively easy to learn at the time, it quickly moved from campus to society and became the first choice for beginners to learn computer programming.

  Later computer engineers and experts from some computer companies developed er_basic based on the collaboration of Wozniak and two other colleagues.

  For beginners, BASIC is obviously the best choice, which was also the most popular programming language in the 1980s.

  Lin Hong directly typed two lines of code under the command prompt:

  01_print_“hello,world!”

  02_end

  Then he directly typed in the "run" command on the third line.

  Only to see the next line, "Hello, World!" appeared immediately.

  "Hello, world!" Lin Hong excitedly clenched his fist and loudly read it out in English according to the display on the monitor.

  Although the manual had such an interface result long ago, he felt different when he operated it himself.

  This is just an extremely simple little program. No matter what language you learn, for every beginner learning programming, the first program is basically always "Hello, World". This has basically become a convention among programmers.

  "Hello, world!"

  This is such a simple program that even without any foundation, beginners can easily understand it, but it's not pale, it has a distinct feature of programming language, reflecting the most basic ideas and characteristics of programming languages.

  This is like a loud cry of beginners in the computer world, marking their entry into this magnificent man-made world, containing declarations and also the joy of beginners who successfully wrote their first computer program in life.

  Lin Hong's current mood is like this, he feels that these two simple words just expressed his current voice. Han first used this example when writing "B Language (C Language predecessor) Tutorial and Guide", later he used this example again in the C language tutorial, after which it spread widely.

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