{"id":12034,"date":"2025-10-10T02:00:00","date_gmt":"2025-10-10T06:00:00","guid":{"rendered":"https:\/\/www.both.org\/?p=12034"},"modified":"2025-09-26T14:50:01","modified_gmt":"2025-09-26T18:50:01","slug":"print-hello-world-in-color-with-conio","status":"publish","type":"post","link":"https:\/\/www.both.org\/?p=12034","title":{"rendered":"Print ‘Hello world’ in color with conio"},"content":{"rendered":"
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When I first started using DOS, I enjoyed writing games and other interesting programs using BASIC, which DOS included. Much later, I learned the C programming language. I immediately loved working in C! It was a straightforward programming language that gave me a ton of flexibility for writing useful programs. In fact, much of the FreeDOS core utilities are written in C and Assembly.<\/p>\n\n\n\n

So it’s probably not surprising that FreeDOS includes a C compiler\u2014along with other programming languages. The FreeDOS distribution includes several C compilers you can use to learn C programming, including Bruce’s C compiler (a simple C compiler), the IA-16 port of GCC (requires a ‘386 or better CPU to compile, but the generated programs can run on low-end systems), and the OpenWatcom C compiler.<\/p>\n\n\n\n

Programming in C on FreeDOS is basically the same as C programming on Linux, with two exceptions:<\/p>\n\n\n\n

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  1. You need to remain aware of how much memory you use. Linux allows programs to use lots of memory, but FreeDOS is more limited. Thus, DOS programs used one of four memory models (large, medium, compact, and small) depending on how much memory they needed.<\/li>\n\n\n\n
  2. You can directly access the console. On Linux, you can create text-mode mode programs that draw to the terminal screen using a library like ncurses. But DOS allows programs to access the console and video hardware. This provides a great deal of flexibility in writing more interesting programs.<\/li>\n<\/ol>\n\n\n\n

    The OpenWatcom C compiler is a great compiler for first-time programmers, so let’s start there. If you don’t have this installed by default, you can install it from the BonusCD in the FreeDOS 1.4 distribution.<\/p>\n\n\n\n

    Programming on DOS<\/h2>\n\n\n\n

    To briefly describe a few of the most useful functions available to you in the Open Watcom C compiler, use these functions from conio.h<\/code> to read data directly from the keyboard:<\/p>\n\n\n\n