Introduction to Free Software and Operating Systems
Terms and technical Facts
Increased Security with Free Operating Systems

Operating systems tend to have an increasingly ex­ten­sive program code base, which increases the rate of prob­able errors. Closed proprietary operating systems do not offer the possibility of open quality control and er­ror analysis. The FSF even maintains great privacy con­cerns (“The FSF's statement on Windows 10”). The source code of free systems, on the other hand, is com­plete­ly open. Their software architecture can be sub­jected to a systematic error analysis.

This introduction illustrates essential terms on the sub­ject area Free Software and contains brief profiles of popu­lar free operating systems. In addition it is il­lus­trat­ed, how old computers can be turned into productive desk­top computers, with the help of specialized dis­tri­bu­tions.

The Source Program Text

Operating systems and other computer programs are mainly written in programming languages that are easy for people to read, e.g. in C and in C++. This original pro­gram text, also called source code, is then translated into binary code, creating an executable program that is readable by the computer (see also “High-level pro­gram­ming language” and “Machine code”).

Binary Code resp. Machine Language

Above a certain size, programs that are available ex­clu­sive­ly in binary code (machine language/machine code) can only be read and edited ineffectively. Their handling is then no longer practicable and a retranslation or dis­as­sem­bly is only limited, or, if parts of the program code were also encrypted, no longer possible at all. A similar situation exists when a manufacturer hermetically seals his device in such a way that the user can no longer carry out any repairs and cannot gain any insight into the mode of operation.

Free Software

Free application programs and operating systems are avail­able free of charge, both as translated, executable binary versions and as source code. The original code may be adapted and modified, and these changes may be redistributed free of charge. Different license models are used. Non-free, so-called proprietary software, can only be obtained as binary code version.

Free software must not be confused with freeware. The term “freeware” is not clearly defined. It may or may not refer to “free software”. It tends to refer predominantly to software that is distributed free of charge, but whose program text remains unpublished. There are several categories of free and non-free software.

Source Code Control and Freedom from Back Doors

Secretly installed software backdoors could make data and industrial espionage possible, in extreme cases even targeted sabotage, especially if they are dis­cov­ered by third parties.

Due to a lack of source code availability, non-free pro­grams cannot be subjected to a public security analysis. Their operational readiness increasingly depends on activation servers of the manufacturer. If they fail, even legally purchased software will only work in a limited way or even be shut down completely. This scenario has already occurred several times in recent years, docu­men­ted in numerous news archives. Among other things, thousands of operating systems only functioned to a limited extent. Even security pro­grams already refused virus signature updates due to activation server prob­lems.

Source code openness alone does not guarantee automatic verification of the program code structure by third parties, and, like operating systems, application programs tend to become more and more com­pre­hen­sive overall source code, which constantly

increases their maintenance complexity. In addition, malicious code programs that have been analyzed have repeatedly attracted attention for their sophistication, elegance and discretion, making their discovery difficult or in some cases virtually impossible. However, the error detection probability of free software is often higher because its program text is accessible for analysis.

Corrupted electronics, known or unknown “advanced” hardware architectures with factory installed “remote maintenance functions” are the other side of the problem. Depending on the application, computer island solutions that never connect to the Intranet or the Internet are better suited to minimize the risk of industrial espionage, although it cannot be ruled out that some computer chips and hardware systems transmit data by radio even when the computer is switched off. A whole range of physical aspects must also be taken into account, in particular the problems of radiation and shielding which have been known for a long time.

Complexity and Safety versus Ease of Use

In their pure, original form, programs are controlled by text commands. Desktop-oriented operating systems and programs use graphical user interfaces with natural language menu control. This eliminates the need to learn the actual commands.

Graphical user interfaces and fully automatic functions increase the scope of the program code, which also in­creases the overall complexity and the number of pos­sible programming errors. Less program code is clearer and easier to analyze.

Reducing complexity and applying cryptography con­sist­ent­ly are the guiding principles of the OpenBSD de­vel­op­ers ( Successful in use worldwide for many years, some consider this free Unix/BSD system to be the most secure operating system in the world. Its main areas of application include the high security sec­tor at network and server lev­el, at intranet and internet lev­el (web hosting basic article). OpenBSD basically ex­cludes non-free, undocumented hardware drivers.

The less complex an operating system is, the less fully automatic functions are available, the more training time

is required. Normal users who are not familiar with (soft­ware)​technical computer aspects full-time or as part of a hobby unfortunately do not have this training period. When choosing a free operating system, a compromise must therefore be found between ease of use and security. Of course, GNU/Linux operating systems with maximum auto­mat­ic comfort are also available, e.g. Ubuntu LTS versions, on which the Linux Mint operating system, which is particularly interesting for MS Windows users, is also based.

When using proprietary operating systems, your influence on security aspects is extremely limited. Ultimately, you remain at the manufacturer's mercy, even if you have ex­ten­sive programming skills and can perform partial analy­sis, customization, and maintenance at the operating sys­tem code level, although this would be impractical given the size of the program code today.

Manufacturers of proprietary operating systems and ap­pli­ca­tion programs could theoretically offer software main­te­nance backdoors to certain organisations. Such access would then provide complete access to a computer sys­tem.

Free Operating System Alternatives and “Binary Blobs”

In many industries one is absolutely dependent on a proprietary locked software, since there is (still) no equivalent free alternative. The desire to earn a living by writing software and protecting it is also understandable. However, computer security is just as justified, and countless commercial software manufacturers also use completely legally open source free program code, locked away in their software architectures. Some Free Software licenses allow such inclusion in proprietary closed code.

For many areas, there are fully-fledged or, for the majority of users, completely sufficient free alternatives. A software directory reports a total of approx. 250,000 free projects (external article: “Ohloh Open Source Directory Passes 250,000 Projects”, January 28, 2009). Especially advantageous: There are not only one, but several free alternatives for numerous application purposes. Even operating systems specially optimized for very old computer generations are developed and maintained.

Most so-called free operating systems contain numerous optionally installable binary code drivers, e.g. graphics card drivers, for which the manufacturer has not published any source code or documentation. This results in security risks and maintenance problems. Although these binary code drivers may be reproduced and distributed free of charge and under a "Free Software" license, due to the source code undocumented nature of such programs, which are practically unmaintainable, they are binary blobs (OpenBSD image and text story “Blob!”). The inclusion of such drivers is not malicious, operating system distributors only intend to provide broad hardware support. However, security risks cannot be eliminated.

Dual Boot Option

Completely non-free and free operating systems can be operated in parallel on one hard disk. Some free operating systems, e.g. Ubuntu, offer a fully automatic partitioning of the hard disk during the installation, set up themselves independently beside an already existing system and install a selection menu, a so-called boot manager.

Operating System Recommendations

OpenBSD can be used as a desktop system, but the normal user needs too much training. From the large number of free operating systems or distributions – several hundred – three are short-portrait. Taking into account the desktop comfort requirements of the “stand­ard user”, the following systems are recommended, for example, which can also be downloaded free of charge from the Internet as anISO image and tested without installation.

These distributions form a small section of the world of free operating systems, the large number of which is mainly due to specializations in application purposes and professional sectors. In specialized distributions, the underlying system architectures have been op­ti­mized for maximum performance for certain areas of use, and a specialized collection of application programs is supplied as standard, sometimes even preconfigured for certain workflows.

However, the use of free programs is not linked to the use of a free operating system, most free programs are also available free of charge in a version for MS-Windows and for MacOS.

First-class universal operating systems: Ubuntu LTS versions and Linux Mint

Based on De­bi­an GNU/Li­nux, first re­leased in 2004, Ubuntu Linux ( offers a mature, comprehensive desktop experience: fully automated installation, pre-con­figu­ra­tion, and hardware/device detection. Since its inception, the greatest possible ease of use has been the focus of this popular GNU/Linux distribution for desktop computers and folding laptop computers, probably the most widespread worldwide.

Ubuntu is as easy to use as two popular proprietary operating systems in almost all respects; in several respects it offers far more possibilities and convenience. Many thousands of programs for different applications can be downloaded for free and managed centrally.

KDE, Cinnamon and Gnome belong to the most popular desktop interfaces, the appearance can be adapted comprehensively to personal preferences; Gnome is currently pre-installed by default (status: 2019). In addition, there are numerous other free desktop en­vi­ron­ments available, including computational power-saving ones that also run smoothly on old computers.

The choice of an LTS version is recommended. These so called “Long-​term-​sup­port”-​di­stri­bu­ti­o­ns are released every 2 years and are provided with updates and patches for five years (see also the WP-article Ubuntu version history).

Ubuntu manufacturer Canonical provides detailed information on hardware compatibility, certified complete systems, and individual components in the hardware database (Component catalog).

The widespread Linux Mint ( based on Ubuntu-LTS is particularly suitable for users switching from MS-Windows. Install the fonts commonly used under MS-Windows (search term: ttf-mscorefonts-installer Linux Mint).

TrueOS ( is FreeBSD (, a true Unix in a desktop optimized version. In addition to the many thousands of freely available programs for FreeBSD (Ports system), GNU/Linux programs also run in Linux emulation mode. Users are free to choose which user interface (desktop) they want to work with.

The code audit (program code analysis, quality assurance) of free BSD systems and the resulting stability and security are legendary, many commercial software vendors use FreeBSD in-house. TrueOS offers a highly convenient installation, operation and management. Hardware support is not yet as comprehensive as Ubuntu Linux, but this is only a matter of time.

Matthew D. Fuller has written a comprehensive, in-depth juxtaposition of BSD and GNU/Linux: “BSD vs Li­nux”.


gNewSense (, News-Blog) has set itself the goal of freedom from any black program code, binary blobs. Firefox, Thunder­bird and other Mozilla products are available in a specially adapted and renamed version. gNewSense is the only truly free operating system that can be installed and used by normal users. It is one of the few 100 % bi­na­ry blob-free distributions, officially recommended by the Free Software Foundation (

The FSF takes a very sceptical view of proprietary software and proprietary operating systems, so does gnu.​org.

WP-articles and -overviews: “Category:Free software operating systems”, “Com­pa­ri­son of open source ope­ra­ting sy­stems”.

Freely selectable Desktop Environment, Design Principles, Background Images

The flexibility of unixoid op­er­at­ing system distributions gives users complete free­dom of choice. The default desk­top environment selected by the respective dis­tri­bu­tion may or may not be suitable. You have the freedom to install any number of desktop environments at the same time and select them when logging in with your user account or to preset them as the default desktop environment. The distribution preselection of standard programs is not restrictive, you can install your favorite programs at any time.

Take a look at the WP-overview “Ca­te­gory:Free desk­top en­vironments”, almost every article listed in English is al­so available in a Ger­man version (click and select “Ger­man” on the left); take a look at the article “Open​Desk​”.

Desktop environments follow design philosophies, dif­fer­ent functionality principles are applied. Among the en­vi­ron­ments offered, there is a high probability that there are also those that meet your personal pref­er­ences and requirements. Get overviews, read the WP articles “Cin­na­mon (software)” and “MATE (software)”.

You may already have a favorite user interface of a commercial operating system and want as similar as possible on a free operating system, including the familiar background image of current or older MS Windows and MacOS systems. These are available in the most different variants in the Internet, in more or less similar or identical image versions, as well as in original versions. For ex­am­ple, Wall​ offers various “Desktop Wall­pa­pers” in different screen and resolution formats for down­load, including the “Cate­gory Mac” (including “OS X Yo­semi­te HD Wall­pa­per”, “Apple Mac OS X High Sierra HD Wall­pa­per”, “macOS Sierra HD Wall­pa­per”, “macOS Mojave Day HD Wall­pa­per”, “macOS Mojave Night HD Wall­pa­per”) and “Win­dows Wall­pa­pers”. See also the cat­ego­ry “Land­scape Wall­papers” “Landscape Wall­papers” (approx. 140 pages) if you like atmospheric landscapes as background.

Some Linux distributions aim to be as similar as possible to MacOS in appearance and functionality: “5 Linux Distri­butions That Look Like MacOS”.

Modern Operating Systems for old Computers
Modern Free Software for old Hardware

In the world of free soft­ware there is not only one software for numerous application areas. Often several alternatives are offered, including extremely lean programs. Strict selection of such lightweight li­bra­ries, win­dow man­ag­ers (com­par­i­son), and applications results in a performance-optimized overall system, which on the one hand covers everyday tasks and on the other hand is of interest for many educational sectors. Especially for institutions that only have small financial means, but still want to get maximum performance out of old and very old hardware, with up-to-date, modern and constantly maintained software. Entire IT infra­struc­tures can thus be built from used hardware, including servers at the in­tra­net level.

The large number of Linux dis­tri­bu­tions is due in particular to the specialization in application purposes and occupational sectors. With regard to old hardware, this means that you can use the maximum power of your older computer. There are numerous gradations with regard to the respective total computing power consumption of the different Linux operating systems. Select the most suitable distribution for you, and then put together lightweight application programs according to your requirements and taste.

Combine old Computers with new Hardware

Collections of free, alternative driver programs, such as the printer driver collection Gutenprint<7a>, enable the parallel operation of current peripheral devices (printers, scanners, etc.) together with old computers. Internet use is also possible. If the motherboard of an old computer does not have an integrated network card, it can be made Internet compatible by purchasing a separate network card. USB network cards are available for old laptops. In general, almost all types of adapters are available, in many directions. They also allow you to use modern storage media, such as memory card readers (SD memory cards, USB mass storage devices, etc.); USB hubs are also available. The technical expansion and customization options are very flexible.

Internal hard disks can be replaced by new models with much larger storage capacities, and SSDs can also be installed for SATA and IDE connections: By using solid-state disks, the loading of the operating system, programs and data is greatly accelerated. SSDs are inexpensive and available in a variety of sizes. The use of a factory fresh hard disk, internal or/and external (USB and others), upgrades the computer system.

A large Selection of fast and lightweight Application Programs
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You also have many powerful alternatives to choose from when selecting programs, which run smoothly and quickly on older computers. Instead of Firefox, you can use the free Chrome variant Chromium, for example, or other, even more lightweight, fast web page readers such as Xombrero. Use ad block filters to stop power-consuming, unnecessary animations. “Comparison of lightweight web browsers”.

Email for private and business use: Use a local email program on your home computer instead of CPU-intensive web­mail if you are working with an older or very old computer, or if your Internet connection is slow or data transfer volume is limited. You save both computing power and online time. In contrast to webmail, this way of handling electronic mail also represents professional e-mail management under both protocols, IMAP and POP.

If you want a Personal Information Manager, first test whether your computer is suitable for the use of “Evolution” (official site), the often fully-fledged alternative to Microsoft Outlook. Other e-mail programs can be modularly equipped with similar functionalities, via extensions and plugins.

Get an overview of: “Category:Free email software”, “Comparison of email clients”, “Category:Free personal information managers”, “Category:Free calendaring software”.

The local email program Claws Mail (WP-article) is an excellent, lightweight alternative to Mozilla Thunderbird. All these programs can be easily tested and downloaded for free. The Lubuntu package manager gives you access to all programs for Ubuntu.

Teletype Message: From the very beginning, communication services have been a central part of the Unix world. Free instant messaging programs, such as Pidgin, can handle numerous communication protocols, including the XMPP protocol suitable for Internet telephony. Further information: “Category:Free instant messaging clients”, “Ex­ten­sible Mes­sa­ging and Presence Pro­to­col”, “Ca­te­go­ry:Free XMPP clients”.

Office software: The slim, high-performance word processor Abiword, together with the spreadsheet program Gnumeric and free PDF applications, provides a good alternative for many basic office tasks such as

writing letters, articles, brochures, scientific papers and other types of documents. Further Information: “Ca­te­go­ry:Free word pro­ces­sors”, “Ca­te­go­ry:Free spread­­sheet soft­ware”, “Ca­te­go­ry:Free of­fice soft­­ware”, “Ca­te­go­ry:Open-source of­fice suites”, “Ca­te­go­ry:Free ac­coun­ting soft­ware”, “Ca­te­go­ry:Free plot­ting soft­ware”, “Cat­e­go­ry:Calendaring software”.

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Graphics: mtPaint is an excellent lightweight image editing software for the post-processing of photos, scanned images and documents, and for the creation of graphics. Its scope of performance is considerable and also includes the layer technique. Instructions: The mtPaint Handbook. mtpaint, XPaint and other free graphics applicationsy are also suitable for creating and editing screenshots.

If you need more graphics functionality, install the meanwhile CMYK-supporting GIMP image editing program. From the huge repertoire of free software packages you can install and uninstall any program fully automatically and try out how fast and fluid it runs on your older computer.

Diagrams, schematic and technical drawings, as well as circuit and printed circuit board designs are predominantly designed with vector graphics based programs. Also in these areas several lightweight alternatives are available, for example the free vector graphics program xfig. Overviews: “Category:Free vector graphics editors”, “Category:Free diagramming software”, “Category:Free electronic design automation software”, “Category:Free computer-aided design software”.

Practical File Management: Classic “drag and drop” of files is of course also possible under free operating systems. The powerful lightweight programs PCMan File Manager (pre-installed), ROX-Filer and Thunar stand out from the crowd of free graphical file managers due to their low resource requirements.

Free operating system distributions are traditionally excellent for learning programming. Java is supported by the free GNU Compiler Collection and the free OpenJDK. The popular, universal Python is also almost always pre-installed. By default, a large number of software and tools are included, including free text editors and network-relevant programs. They form a good basis for information technology teaching and training at educational institutions.

Learning Languages,
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Even without Internet access, you can benefit from the possibilities of the computer when learning a language. Download free or free learning materials from public Internet places and save them on a USB stick.

Even video films from Internet video portals such as Youtube can be downloaded and saved and then watched at home on your computer, for example with the free add-on “Video DownloadHelper”, or with the free program “XVideoServiceThief”, with a corresponding extension for the Internet browser Chromium, or with another software. Ask the staff of your Internet cafe or other institution about the possibility of making certain basic extensions available for web browsers. Use free dictionaries and translation tools, some of which are also available in a free offline version, e.g. Beolingus and and QuickDic.

E-Letters can be created on your home computer, for example as an extensive illustrated text document file, which you later simply attach to the e-mail, or whose

text you copy into the e-mail body. Sound files for texts can also be recorded at home on the computer.

Overview of free software audio recorders: WP article “Category:Free audio editors”. In the Internet café you then take your prepared message and send your letter together with the audio file by e-mail to your language penpal. You can also download the message and sound file sent to you from your pen pal's e-mail account, save it on your USB stick and listen to it on your home computer.

Numerous resource-saving free programs are also available for MS-Windows, so that you can also use this operating system optimized for older computers, with a self-assembled selection of lightweight application programs that run smoothly and fast. However, Microsoft's security update deployment ends after a certain period of time. Modern free lightweight operating systems for old hardware, on the other hand, are constantly maintained and updated, especially for old computers.

Advanced users can check which daemons or system services are started when the computer boots, and then disable any unnecessary programs that run in the background by default.

Powerful Free Mathematics Software, also for old computers

Schools today use powerful specialized calculators. Independent of this, it is of great advantage to know the basic functions of a free com­put­er algebra system if one wants to check the solutions of complex equations and other mathematical problems with the help of the computer or illustrate them with graphs and three-dimensional graphics, in school operations, in education, in study, in science and in general in everyday working life. The Python-based Saga interfaces with a number of long-standing, mature free mathematics programs, making it a powerful, universally applicable computer algebra system. However, its resource requirements are not insignificant, which probably makes it not always performant enough on very old computer systems despite its platform-independence.

SymPy, on the other hand, is 100 % Python-based and therefore as platform-independent as possible. Together with Pyglet, it forms a modern, well-maintained computer algebra system that covers all elementary functions for mathematics teaching. Thus, even for very old computer systems and for financially weak educational institutions, a powerful, free and free mathematics software is available worldwide. Sympy is used by numerous universities, including the Mathematical Institute of Freiburg University.

Sources of information: Offical site of SymPy, doc­u­men­ta­tion, Frequently Asked Questions, WP-article “SymPy”, web presence of Pyglet.

Knowledge of Python notation is an advantage. Python (official site) is an easy to learn, universally applicable scripting and programming language that is supported in many subject areas worldwide. A large number of software programs offer Python interfaces and it can also be used server-side for functions of webpages.

Free programs for teaching and education: “Ca­te­go­ry:Free edu­ca­tional soft­ware”, “Por­tal:Free soft­ware”.

Operating System and Distribution Overviews

Xubuntu, equipped with the desktop interface XFCE, and Lubuntu with the user interface LXDE, are official Ubuntu derivatives (Debian-based). Ubuntu operating systems have the highest level of user comfort and full automation. Xubuntu is relatively resource-friendly. The first-class Lubuntu consumes considerably less computing power and memory. Since both operating systems are available free of charge, you can try out which distribution is more suitable for you.

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Lubuntu information: Official site">Official website, WP-article “Lubuntu”, pre-installed standard application programs, OSnews article from 01 March 2011 “Lubuntu: Finally a Lightweight Ubuntu!”, Linux magazine article from 09 September 2011 “Lubuntu: Floats Like a Butterfly, Stings Like a Bee”

“Operating sy­stems for really, really old com­pu­ters”, lists a very comprehensive list of specialized Linux distributions, “Lightweight Linux Distributions” contains further central references.

The operating system Con­no­chaetOSConnochaetOS is developed especially for very old computers. The included standard program collection includes application software for all basic computer tasks: Word processing, spreadsheet, web page reader (browser), e-mail program etc. (official news section).

News excerpt (Announcements) for the current operating system version 14.2, which was released on August 26, 2016, added additional hyperlinks to the text: “[...] As always it contains only free/​libre software as defined by the Free Software Foundation (FSF). We are now using our own deblobbed Linux kernel, named "kernel-free" based on the de-blobbing mechanism done by Debian GNU/​Linux. ConnochaetOS contains:

In our slack-n-free repo we provide the current versions of Iceape [renamed Internet ap­pli­ca­tion suite SeaMonkey (Browser, E-Mail, et al)] and Icedove, the brand-new qt5-​web­engine based web browsers qupzilla and otter-​browser and libreoffice 5.1.4 [...]”

Article about ConnochaetOS (June 04, 2015): “ConnochaetOS Makes Slackware Truly Free and a Bit Easier”, Jack M. Germain.

Another powerful operating system is Delicate-Linux is De­li­cate-​Li­nux: title page, (further website), forum, De­li­cate-​Wi­ki.

In addition to the graphical “desktop environments” and application programs, Linux distributions also contain “text mode software” with a “text-based user interface” as standard. They are extremely powerful and belong to the preferred tools of many users, administrators, IT professionals and scientists.

Websites and recommended articles about text mode programs: „ :: freie Text­mode-Soft­ware”Websites about text mode “Con­sole app­li­ca­tion”„Text-based (compu­ting)”“Shell (com­pu­ting)”“Command-line interface” An excellent introduction: Floss Ma­nu­al “In­tro­duc­tion to the Com­mand Line” “GNU Screen”“Computer terminal”.

Introductory Articles on Specialized Distributions for old Computers

Various organisations are committed to promoting educational equality, using free software and used hardware, for example “Free Geek” in the U.S.A.

Free Software traditionally enjoys outstanding international language support, including free operating systems.

Screenshot of Lubuntu 12.04

For almost every area there are several different application programs for one and the same task. The programs shown here are only a small

part of the thousands of free applications available for Lubuntu (GNU/Linux or Unix/BSD software).

A small selection of office applications.
Text shown in Abiword word processor:
Text processing programs offer extremely
extensive design possibilities, whose
effective use a longer training period
is required. Long-term stable software
proves to be advantageous here.
(Operating system) platform independence 
and the mastery of a truly 
open, suitable for archiving
document formats are further 
central criteria for use in 
heterogeneous corporate networks and administration.'

Office applications: Word processing Abiword, spreadsheet Gnumeric, calendaring software Osmo, calculator Galculator.

October 17, 2022

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