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GAMES IMAGES OPERATING SYSTEMS LLVM AI Tensor Flow DATA DOSBox GNU Thunderbird VLC 7-Zip FFmpeg VIDEO SPICE DEV ARCHIVES GIMp 3D OpenPGP FreeCAD Notepad++ Open-Source Software Open Street Maps Blender PRODUCTIVITY AV1 SIMS FreeDV EMAIL OPUS By Dr David Maddison, VK3DSM Firefox Linux Audacity CHROMIUM WINE AUDIO LibreOffice WEB PCB You may have used free/open-source software in the past, but you might not be aware of the variety and quality of free software available. You could also be wondering: why would anyone go to the huge effort of creating software, only to give it away for free? I n our article on Repairable Electronics, we described open-source hardware, that is, hardware where the plans and parts are all freely available (July 2024 issue; siliconchip.au/Article/16320). We also briefly discussed open-source software in that article, because of the way it relates to the hardware. This article will provide a lot more detail on that subject. Part of the inspiration for this article is the wide variety of excellent free and open-source software that’s available. Many people think that they need to pay for software to get something that’s useful and works well. While it’s true that some free/opensource software can be ‘unfinished’, much of it these days is actually very good with decent stability, many features and possibly a very polished user interface. While modern commercial software can be very capable, compared to earlier software, it can be quite ‘bloated’ (taking up a lot of CPU, memory and disk space), buggy, insecure, concerns about privacy (eg, spying on users), or can force users to create online accounts. Because of this, many people today are looking to alternatives. The high cost of much commercial software is now also a concern, especially as some of it is no longer available for purchase. You may have to subscribe to it, at a cost that can increase rapidly and unpredictably. In some cases, this can mean paying 10 Silicon Chip more in one year than you used to pay for a piece of software outright (ie, that you could use more-or-less indefinitely). Due to the poor testing of much commercial software, many end users don’t like being unpaid testers. Software bugs cost a lot of time and money, as does endlessly upgrading hardware to cope with the demands of often inefficient and bloated software. One big advantage of using opensource software is that the source code can be audited by third parties to ensure that it doesn’t do anything nefarious and it isn’t full of security flaws. Another reason to use open-source software or operating systems is that they may support older versions of hardware than commercial versions of software. For example, many people find their perfectly good and relatively new printers or scanners become obsolete with new operating system upgrades. The latest version of Linux will run happily on 10-year-old hardware. The same cannot be said for the latest version of Windows, which often won’t even install on a computer that’s just a few years old! Another great reason to use opensource software is that it often has cross-platform support, meaning it will typically run on Windows, Linux or macOS. That makes it more universal and also means that you can decide Australia's electronics magazine to change operating systems (eg, from Windows to Linux or macOS) and continue to use the same software. The interfaces are usually even similar across platforms. With open-source software, if it doesn’t support a platform you use, since you have access to the source you may even be able to ‘port’ it to a different operating system. Having said that, it usually isn’t a trivial process. For all of the above reasons, a social movement has developed for people to voluntarily get involved in the production and distribution of free software. It isn’t necessarily inferior in terms of features to commercial software, either. FOSS One alternative to traditional commercial software is so-called “free and open-source software” or FOSS. FOSS is software that is distributed “under a license that grants the right to use, modify, and distribute the software, modified or not, to everyone free of charge”. The mere availability of source code does not necessarily mean software is FOSS unless the other conditions are met. FOSS is a broad-ranging term for software that is mostly distributed under the terms of licenses from either the Free Software Foundation (www. fsf.org) or the Open Source Initiative (https://opensource.org/osd). siliconchip.com.au These organisations have slightly different philosophies. The Free Software Foundation The Free Software Foundation defines four essential freedoms of free (FOSS) software, originally developed by Richard Stallman: 1 The freedom to run the program as you wish, for any purpose. 2 The freedom to study how the program works, and change it so it does your computing as you wish. Access to the source code is a precondition for this. 3 The freedom to redistribute copies so you can help others. 4 The freedom to distribute copies of your modified versions to others. By doing this, you can give the whole community a chance to benefit from your changes. Access to the source code is also a precondition for this. You can read a collection of Stallman’s essays on open-source principles at www.gnu.org/doc/fsfs3-hardcover.pdf Open Source Initiative software The Open Source Initiative defines open-source software according to the ideas of Bruce Perens as requiring the following: 1 Free distribution. 2 The source code must be freely available and not obfuscated in any way. 3 Derived works must be allowed. 4 Integrity of the author’s source code must be maintained, with limitations on modifying it or indicating when it is. 5 No discrimination against people or groups. 6 No restrictions on where or how the software is used. 7 The same license applies to all people to whom the software is distributed. 8 The software license applies to all products derived from a particular software distribution. 9 The license may not restrict what software is distributed along with a particular operating system ‘distribution’. 10 The license must be technology neutral. Examples of software licenses from the Open Source Initiative are Apache License 2.0, BSD 3-Clause and BSD 2-Clause Licenses, all versions of the GPL (GNU General Public License), siliconchip.com.au all versions of the LGPL (GNU Lesser General Public License) and Mozilla Public License 2.0 (used for Firefox and Thunderbird, among others). Licensing Both FOSS software and Open Source Initiative software are issued under license agreements, although this doesn’t generally involve any physical paperwork. It is automatic when you download the software, perhaps after agreeing to its terms and conditions. Common open-source licenses used by various organisations include the Apache License, BSD License, GNU General Public License, GNU Lesser Public License, MIT license and the Mozilla Public License. There are two broad categories of license for free and open-source software: permissive and copyleft (see below). Permissive licenses generally come from academia and have minimal restrictions. Copyleft licenses come from the free software movement and typically require distribution of the software and derivative works with attribution and source code. Both types usually have a warranty disclaimer (then again, so does most commercial software). Copyleft Copyleft is a concept of granting certain rights for use of copyrighted works such as sharing, modifying, copying or redistributing them. Author attribution is required and is usually incorporated in the source code files along with full license conditions. Copyleft allows people to freely use the copyrighted product, but does not allow them to own it or earn royalties from it. Naming confusion & ideological differences Both the FOSS and Open Source Initiative have the words “open source” in their names, which leads to some confusion between the two approaches, although this is of little practical consequence. There are important differences between the views of the Free Software Foundation and the Open Source Initiative. A basic difference is that FOSS software is always free, but Open Source is not necessarily so (but usually is). There may be copyright issues or distribution restrictions of various kinds. See www.gnu.org/philosophy/ open-source-misses-the-point.html for more on this. In terms of the practical differences to users of these two forms of software, there are few differences to be concerned with. They are mostly ideological and lie with the proponents of the two movements. There may be costs While the software we talk about is generally free, there may be a cost if it is distributed by a commercial organisation who that offers technical or other support. For example, WordPress is free software, but there are companies that charge for hosting and/or technical support for it. Similarly, there are versions of Linux such as Red Hat Enterprise Linux (RHEL) that cost money. They Fig.1: examples of FOSS software running on Fedora Linux with the KDE Plasma desktop environment: Firefox, Dolphin file manager, VLC media player, LibreOffice Writer, GIMP and KCalc. Source: https://w.wiki/BsLi Australia's electronics magazine February 2025  11 may be used on supercomputers or in major commercial or government enterprises. There can also be charges for some other large enterprise software installations where support by commercial organisations is offered. Public domain software Public domain software was popular from the 1950s to the 1990s. It still exists, but has been mostly replaced by FOSS and Open Source licenses. Software that has been placed into the public domain has no ownership, licensure, or any other restriction placed on it whatsoever. It became mostly obsolete due to changes in copyright laws in the United States and elsewhere with the implementation of the Berne Convention, which meant that all original works are by default copyright protected and required an explicit waiver to enter into the public domain. Freeware Freeware is software that is distributed without charge, but unlike FOSS or Open Source software, the source code is not typically available. Freeware can be full-featured, or it might be from a commercial source, as a type of “sampler” to encourage purchase of a more capable version of the software (eg, see the DaVinci Resolve entry below). It may come with restrictions on the way it’s used. Shareware Shareware is proprietary software that either has a trial version available, or has limited functionality. It might be supported by advertisements or a purchase of a more capable or less restricted version. It might display some mark in the output, such as a watermark or logo. Source code is usually not available. In the rest of the article, we will not necessarily distinguish between FOSS and Open Source software or other types of free software, although we will try to mention which category each entry falls under. ● The Brazilian government, which moved from Windows to Linux. ● Austria, which uses OpenOffice products and Linux. ● The German armed forces, which use Matrix for internal communications. Examples of free and/or open-source software Naturally, it would be impossible to list or review all available software. The following will hopefully give you an idea of the fantastic variety of free and open-source software that’s available. We’ll break down the different types of software into five categories: ● General software, that will be of interest to most readers ● Engineering & mathematical software, that we expect will also be useful to many of our readers ● Operating systems ● Development/back-end software, which will be most interesting to those who are more into computers and software development General software We’ll start things off by covering open-source software available for most common day-to-day tasks such as document editing, web browsing, email etc. Productivity software LibreOffice (www.libreoffice.org & Fig.2) is a free and open-source set of productivity programs including a word processor (Writer), a spreadsheet program (Calc), a presentation program (Impress), a drawing program (Draw), a database access program (Base), an equation editor (Math) and a charting module. It is a ‘fork’ of Apache Open Office, but LibreOffice is more actively maintained and has a few more features. We use LibreOffice extensively as it provides all the features we need with an easy-to-use interface at no cost. LibreOffice Calc is the spreadsheet program that comes as part of LibreOffice. It supports 1,048,576 rows and 16,384 columns. It can read and write Microsoft Excel files, except those parts (if any) that contain Microsoft proprietary Visual Basic for Applications (VBA), which may have to be rewritten in Apache OpenOffice Basic. Notepad++ (https://notepad-plusplus.org) is a free & open-source text editor program that’s intended to be similar to but much more powerful than Microsoft’s Notepad app that comes with Windows. OnlyOffice (www.onlyoffice.com) is a collaborative online office suite that includes document, spreadsheet and presentation editors, plus a PDF creator, editor and form filler. Scribus (https://sourceforge.net/ projects/scribus) is free, open-source desktop publishing software. If you want to publish a book or magazine, it might be a good place to start. Sumatra PDF (www.sumatrapdf reader.org) is a lightweight, opensource PDF reader. Being lightweight, it is much faster to load and use than programs like Adobe Acrobat. Adoption by governments Various governments worldwide have adopted free and open-source software. Examples include: ● Massachusetts, USA, which has adopted the OpenDocument standard. ● The US White House, which uses Linux and Drupal on its web servers. 12 Silicon Chip Fig.2: the LibreOffice Calc spreadsheet program. Source: www.libreoffice.org/ discover/screenshots Australia's electronics magazine siliconchip.com.au Web Browsers Brave (https://brave.com & Fig.3) is a free and open-source browser released under the Mozilla Public License. It is privacy focused with a strong level of privacy protection, and blocks most ads and website trackers with its default settings. Optional ads can be turned on, which earn users “Basic Attention Tokens” that can be used as a cryptocurrency currency token (based on Ethereum) or to make donations to various websites and creators. Chromium (www.chromium.org) is the open-source web browser that Google Chrome, Microsoft Edge, Samsung Internet and Opera are based on. Firefox (www.mozilla.org/firefox) is a privacy-focused free and open software browser that runs on Windows, macOS, Linux, Android and iOS. It automatically blocks most ad trackers. It also works with Google products such as Gmail and docs and offers a “Facebook container” extension (https://addons.mozilla.org/addon/ facebook-container) to stop Facebook tracking you around the web. Screenshots can also be made from within the browser. Firefox is the successor of one of the original web browsers, Netscape Navigator, introduced in 1994. There are also many privacy-focused forks of Firefox such as Librewolf and GNU IceCat. Tor browser (www.torproject.org) has a slogan that goes, “You have a right to SEARCH without being followed”. It is strongly privacy focused and is designed for safe and anonymous web browsing. It operates over the Tor overlay network, itself built with free and opensource software, designed for anonymous communication via ‘onion routing’ through a network of volunteer-­ operated relays which create random paths for your internet data. This is all encrypted, making tracing and tracking of personal data very difficult for hostile parties like malicious hackers. Its main disadvantage is said to be its slow browsing speed due to the nature of the volunteer-operated onion routing it uses. Communications & email Matrix (https://matrix.org) is a communications protocol to provide secure, decentralised instant messaging, Voice over IP (VoIP) signalling and Internet of Things (IoT) siliconchip.com.au Fig.3 (upper): the Brave web browser on several devices. Source: https://brave. com/static-assets/images/optimized/features/images/Browser-2-1.png Fig.4 (lower): a sample screen of the Mozilla Thunderbird email client. Source: www.thunderbird.net communications, including bridging together existing communications. It is used by the French Government and the German Armed Forces, among others. Mozilla Thunderbird (Fig.4 & www. thunderbird.net) is a free and opensource email client and personal information manager. It also has newsgroup integration, a news feed, a calendar (“Lightning”) and an instant messaging client. It will run on Windows, macOS, FreeBSD and Linux. It supports all common email standards such as POP, IMAP, LDAP, S/ Australia's electronics magazine MIME and OpenPGP. The mail file format it uses is MBOX with MSF (Mail Summary File) but emails can be exported in EML format and others such as text, CSV, PDF and HTML. Drawing, painting, animation & image manipulation Blender (www.blender.org & Fig.5) is a well-regarded 3D graphics program that runs on Linux, macOS, Windows and other operating systems. It is suitable for making animated films, 3D art, creating 3D-printed models, motion graphics, visual effects and other uses. February 2025  13 It has become an industry standard program of sorts. Darktable (www.darktable.org) is an open-source digital photography workflow application for that runs on Windows, Linux or macOS. It can also integrate with GIMP (see below). Inkscape (https://inkscape.org) is a vector graphics editor for Linux, macOS and Windows, similar to Adobe Illustrator or CorelDRAW. GIMP (GNU Image Manipulation Program, www.gimp.org & Fig.6) is a free and open-source image manipulation program for Linux, macOS and Windows. It is considered by many to be a substitute for Adobe Photoshop (it can perform many similar functions). It can be used for image manipulation, image editing, free-form drawing, conversion of different image file formats and other tasks. It can also be enhanced using third-party plugins and the use of scripting. A new major version, GIMP 3.0, is planned to be launched soon and includes many improvements, such as non-­ destructive editing, that solve complaints by people who are used to using similar features in Photoshop. There is a good video on the new features at https://youtu.be/1HoZjHn8gVU Krita (https://krita.org/en/ & Fig.7) is a free and open-source graphics manipulation program for raster graphic art and 2D animation that runs on Windows, macOS, Linux, Android, ChromeOS and Haiku. Some people prefer Krita over GIMP as an alternative to Photoshop. Audio, codecs, transcoders & media players Ardour (https://ardour.org) is a (mostly) free and open-source digital audio workstation (DAW) as used by recording engineers and music producers. It’s similar to commercial music production programs you might have heard of, like Ableton Live or Cubase. Audacity (www.audacityteam.org & Fig.8) is a free and open-source audio editor and recorder said to be the world’s most popular program of its type. It works on Windows, macOS and Linux and supports all major audio formats. There are many thirdparty plugins available for it. Codec is short for coder/decoder. It is a piece of software that is involved in digitising, compressing, decompressing, storing or decoding audio or video data and is also used for streaming. Many codecs are proprietary and/ or patented, but many free and opensource codecs have been developed, such as the following: ● AV1 (https://aomedia.org/av1/) is a video codec developed as a royalty-­ free and open-source alternative to HEVC (H.265). ● Codec 2 is a speech codec for low-bandwidth applications at 700-3200bits/s. ● MP3 was developed by Fraunhofer Fig.5: Blender is a 3D modelling suite, but also doubles as a video editor. Source: https://docs.blender. org/manual/en/latest/ getting_started/ about/index.html Fig.6 (below): a sample screen of the GIMP image editing software. (1) main toolbox, (2) tool options, (3) image editing window, (4) brushes, patterns, fonts and history, (5) layers, channels and paths. Fig.7: an example below of artwork made using Krita. Source: https:// krita.org/en/ 14 Silicon Chip Australia's electronics magazine siliconchip.com.au IIS (siliconchip.au/link/ac2n) and originally required licensing fees. Since the patents expired worldwide by 2017 it is now free and open-source. ● Ogg Vorbis (https://xiph.org/ vorbis) is a free, open-source alternative to MP3. They also published FLAC, a popular lossless audio codec, plus two video codecs, Theora and Daala. ● OpenH264 (www.openh264.org) is an open-source implementation of the standard H.264 video compression system by Cisco Systems. ● Opus (https://opus-codec.org) for audio compression, including speech. ● uvg266 is an open-source H.266 video encoder (https://github.com/ ultravideo/uvg266). ● x264 and x265 are a free & opensource video encoder for H.264 & H.265 respectively. ● VPX (www.webmproject.org/ tools) is a free & open-source implementation of the WebM video codec. FFmpeg is another important opensource project that combines numerous open-source codecs and related software to create a cross-platform video & audio recording/converting/ streaming/playback library. It is used by many open-source media players. Handbrake (https://handbrake.fr) is a popular open-source video encoding and transcoding tool. It runs on Windows, macOS or Linux and can convert from just about any video format to any other. The media player mpv (https:// mpv.io & Fig.9) has an opaque control scheme, but provides a lot of control for users who want to tinker. VLC (www.videolan.org/vlc) is a multimedia player that can play an enormous variety of media file formats, discs, webcams, devices and video and audio streams and comes with the necessary codecs for most applications. It runs on platforms such as Android, Linux, iOS, macOS, Unix and Windows. Video editing, streaming & capture DaVinci Resolve is not open-source but it does have a free version (www. blackmagicdesign.com/products/ davinciresolve). You have probably seen it advertised in this magazine; it was developed by Australian company Blackmagic Design (based in Melbourne). We have used it and think it is excellent. There is a paid version that would be great for professional siliconchip.com.au Fig.8 (above): a screenshot of Audacity showing spectrograms of an audio clip. Source: https://w.wiki/BsLk Fig.9 (right): a sample screenshot of the mpv media player playing Casablanca, which is in the public domain. Outside of a few basic controls on the bottom bar, everything else requires hotkeys to use. Fig.10: a sample screen from OBS Studio, an open-source video streaming platform. Australia's electronics magazine February 2025  15 Fig.11 (left): a sample screenshot of the video editor Shotcut. Source: www.shotcut.org Fig.12: a sample screen of the 7-Zip compression/archiving program. use; the free version is suitable for a range of tasks from beginners to advanced users. OBS Studio (https://obsproject.com & Fig.10) is free and open-source software for video recording and livestreaming. It runs on Linux, macOS and Windows. It can capture images and video from sources such as the computer screen, windows, images, text, browser windows, webcams, capture cards and others. It is widely used by streamers on platforms like YouTube & Twitch. SimpleScreenRecorder is a Linux screen recorder program to record the operation of programs and games (siliconchip.au/link/ac2o). ShareX (https://getsharex.com) is a free and open-source program for screen capture and sharing of the output to other users. It has been likened to a superior replacement for the Windows Snipping Tool. Shotcut (www.shotcut.org & Fig.11) is a free and open-source cross-­ platform video editor. It runs on Linux, macOS and Windows. It offers numerous features and supports a wide variety of formats. Among many uses, it could, for example, be used to make YouTube videos. Even though the final version of VirtualDub (www.virtualdub.org) was released in 2013, it is still a popular video processing and stream capture program with hundreds of third-party plugins written for it. Forks (additional developments branches) have been produced for VirtualDub, such as VirtualDub2 (www.virtualdub2.com). Compression and archiving 7-Zip (www.7-zip.org & Fig.12) is a free and open-source file compression 16 Silicon Chip and archiving tool that achieves greater compression than standard ZIP archives (although it also supports the ZIP format). It was developed by Igor Pavlov and first released in 1999. There is a Windows graphical (GUI) version, plus a command-line version for Linux and macOS. It supports the following formats: 7z (its own format), GZIP, XZ, BZIP2, WIM, ZIP and TAR. It can also unpack (but not pack) files in APFS, AR, ARJ, CAB, CHM, CPIO, CramFS, DMG, EXT, FAT, GPT, HFS, IHEX, ISO, LZH, LZMA, MBR, MSI, NSIS, NTFS, QCOW2, RAR, RPM, SquashFS, UDF, UEFI, VDI, VHD, VHDX, VMDK, XAR and Z formats. Files can also be encrypted. The 7z format uses LZMA and LZMA2 compression, and files have a self-extracting capability. Cross-platform software Wine (www.winehq.org) is a compatibility layer for POSIX-compliant operating systems like Linux, macOS and BSD to enable Windows applications to run on them. One of its advantages is that it will run early Windows programs as far back as Windows 3.1, which will probably not run on current versions of Windows, so it is a way to continue to use legacy programs that may not have a current equivalent. WINE, along with associated tools like Proton, allow many Windows games to run on Linux. This has made it quite a popular gaming platform; for example, the Steam Deck portable gaming system runs Linux and has access to thousands of games, many of which were only designed for Windows. Australia's electronics magazine File transfer software FileZilla (https://filezilla-project. org) is a free and open-source file transfer application for Windows, Linux and macOS. It supports the FTP and FTPS (FTP over SSL/TLS) protocols and can connect to SFTP servers. There is also FileZilla Server for creating FTP/FTPS servers. FreeFileSync (https://freefilesync. org) is a freeware program for folder comparison and synchronisation. It’s useful for creating backup copies of files or synchronising sets of working files between different locations. It is open source and available for Linux, macOS and Windows. Donors get access to a version of the program with some additional features. We use it and find it quite good. LocalSend (https://localsend.org) is an open-source, cross-platform file sharing system, including support for transferring files between mobile devices and computers using Bluetooth. NextCloud (https://nextcloud.com) is a content collaboration program that provides functions like Google Drive and similar when used with office suites like integrated Collabora Online or OnlyOffice. ProjectSend (www.projectsend.org) is a private web-based file sharing program that runs from a server. Encryption software Cryptomator (https://cryptomator. org) is used for encrypting cloud drives from the client’s side. That way, if the data on the cloud server is compromised, it is still safe as only the client holds the encryption key. It is available for Android, Linux, iOS, macOS and Windows. siliconchip.com.au Fig.13: part of the Open Street Map map of Melbourne. Note how even buildings are shown. GnuPG (GNU Privacy Guard, https:// gnupg.org) is an encryption suite that uses the OpenPGP standard (see below). KeePass (https://keepass.info) is a free and open-source password manager purely for Windows. There are also popular cross-platform forks of it such as KeePassXC. OpenPGP (www.openpgp.org) is said to be the most widely used email encryption standard. It is defined by the OpenPGP Working Group of the Internet Engineering Task Force (IETF). It is available for Android, iOS, Linux, macOS and Windows. VeraCrypt (www.veracrypt.fr/en/ Home.html) is for on-the-fly encryption, to create a virtual encrypted disk that works like a regular disk although it is actually a file. In addition, it can encrypt actual disks. Mapping and navigation software Open Street Maps (OSM, www. openstreetmap.org & Fig.13) is a geographic database from the OpenStreetMap Foundation published under an Open Database License. It can be used as a mapping app on mobile phones and is particularly useful in the absence of phone coverage, as the map database is held within the device. It can also be used online. Data is provided by a community of users, and anyone can become a contributor. Fonts and typefaces There are many fonts and typefaces that are open-source and can be used freely without charge or restrictions (see Fig.14). These are available from various sources, such as: https://github.com/showcases/fonts https://open-foundry.com https://fonts.google.com Virtual machine software DOSBox (www.dosbox.com) is a DOS emulator for running old software on modern systems. Proxmox VE (www.proxmox.com), QEMU (www.qemu.org), VirtualBox (https://www.virtualbox.org) by Oracle and Xen (https://xenproject.org) are all popular, free and open-source virtualisation systems that let you run multiple operating systems on a single computer simultaneously. Virus and anti-malware ClamAV (www.clamav.net) is an open-source antivirus engine for scanning emails for trojans, viruses and malware. Other open-source anti-­virus packages exist but nothing full-­featured, likely due to the effort required to constantly monitor for new viruses and malware, develop antidotes for them and to update antivirus files. Video games There are some open-source computer games, such as SuperTuxKart, Mindustry, OpenTTD, UFO: Alien Invasion and OpenXcom. Two we have tried are: OpenTTD (www.openttd.org & Fig.15) is an open-source game based on the commercial game Transport Tycoon Deluxe. Like OpenXcom (below), optional improvements, graphics, music and add-ons have been contributed to enhance the game. While the original Transport Tycoon Fig.14: an example of a typeface called Chunk, reminiscent of old American West woodcut typography. Source: https://github.com/ theleagueof/chunk Fig.15 (right): a screengrab from version 1.9 of OpenTTD. Source: www.openttd.org/screenshots/1.9coldice_3 siliconchip.com.au Australia's electronics magazine February 2025  17 Deluxe only ran under Windows or DOS, OpenTTD can be played on Windows, macOS, Linux and Android. OpenXcom (https://openxcom.org) is an open-source clone of the 1994 DOS game X-COM: UFO Defence (also known as UFO: Enemy Unknown). It is widely regarded as one of the best turn-based strategy computer games of all time. OpenXcom require a copy of one of the original games (XCOM or Terror From the Deep) to run but is a modern Windows program with many bugfixes and improvements over the original. It has the same ‘look and feel’ as the original but is more fun due to many ‘quality of life’ improvements that have been implemented in the spirit of the original. The Battle for Wesnoth (www. wesnoth.org) is another open-source strategy game. application for Linux, macOS and Windows. GNU Octave (https://octave.org/ index.html & Fig.16) is an alternative to MATLAB and mostly compatible with it. It runs on Linux, macOS, BSD and Windows. Gnuplot (http://gnuplot.info & Fig.17) is a free and open-source program to produce 2D and 3D plots of functions, data and data fits. It runs on Linux, macOS, Windows and other systems. It was first released in 1986 and is still under active development. Despite being free and open-source, its source code is copyrighted and distribution of a modified version is not permitted. Such restrictions are permitted under Open Source Initiative licenses. Despite the name, it is unrelated to the GNU Project. Apart from working as a stand-alone plotting program, it is used as a plotting engine by a number of other packages and websites. ParaView (www.paraview.org) is a versatile multi-platform scientific visualisation program developed by Sandia National Laboratories, Kitware Inc and Los Alamos National Laboratory. R (www.r-project.org) is a language and environment for statistical computing and graphics made by GNU. It is similar to the S language and environment that was developed at Bell Laboratories. Miscellaneous There is a Linux project called OpenPrinting (https://openprinting. github.io) to support IPP (Internet Printing Protocol) for printing to local network or internet-connected printers. It also supports legacy printers with appropriate drivers. Engineering & mathematical software Engineering & maths software are heavily dominated by paid and closed-source software such as Altium Designer, AutoCAD and MATLAB. However, there are a surprising number of good alternatives. Computer-aided design software FreeCAD (www.freecad.org & Fig.18) is a free and open-source CAD program mainly for mechanical engineering design, although it can be used in other areas, such as architecture Graphing, visualisation & analysis Gephi (https://gephi.org) is a network analysis and visualisation or electrical engineering. It runs on Windows, macOS and Linux. See the video titled “Learning FreeCAD with These Basic Steps” at https://youtu.be/ rglvJH9z5ng KiCad (www.kicad.org & Fig.19) is a free and open-source electronic design automation (EDA) suite for Windows, macOS and Linux. It can create circuit diagrams and comes with a large library of symbols. It can then perform checks to ensure they follow basic electrical rules such as check for output pin conflicts, missing drivers and unconnected pins and create a “netlist”, which defines the connectivity of the circuit. Once a circuit has been drawn, you can then use it to lay out a PCB, using a built-in library of component footprints (it also has matching 3D models). It can import, export and migrate to and from other CAD (computer-­ aided design) tools. Its PCB editor includes an interactive layout router, side-by-side visualisation of the circuit and layout, design rules checks, trace length tuning for high-frequency designs and a footprint editor. It also has a 3D viewer to examine the proposed PCB design with components in place. LibrePCB (https://librepcb.org) is another open-source ECAD program similar to KiCad. Some people say it has a better library manager than KiCad and is easier to use in other ways. CircuitMaker (www.altium.com/ circuitmaker) and EasyEDA (https:// easyeda.com) are two examples of free PCB design software that we have mentioned in the magazine in the past, but they are not open-source. We reviewed CircuitMaker in the 1 0.8 0.6 0.4 0.2 0 -0.2 -0.4 10 5 10 5 0 0 -5 -10 -5 -10 Fig.16: a sample screen from GNU Octave, an opensource alternative to Matlab. 18 Silicon Chip Fig.17: a sample plot from gnuplot. Source: https://gnuplot. sourceforge.net/demo_5.4/pm3d_lighting.html Australia's electronics magazine siliconchip.com.au Fig.18 (left): a sample screen from FreeCAD v1.0. Source: https://wiki. freecad.org/screenshots Fig.19 (below): a PCB design and 3D rendering underway in KiCad. Source: https://docs.kicad.org/master/ en/pcbnew/pcbnew.html January 2019 issue (siliconchip.au/ Article/11378). 3D modelling software OpenSCAD (https://openscad.org) is a solid 3D CAD modelling program that will run on Windows, macOS and Linux. It is not an interactive modelling program, but rather, the user describes an object using a scripting language (see Fig.20) and renders the 3D model from that. There is a video showing creation of a simple object titled “3D Modeling with Code! The best demo (OpenSCAD)” at https:// youtu.be/KrFttd5D1cw RepRap or replicating rapid prototyper (https://reprap.org) is a project to develop low-cost 3D printers that can print their own components; the Skeinforge ‘slicing’ program was developed as part of this. While Skeinforge now appears to be obsolete, several open-source slicing programs exist. Two we have used are Slic3r (https://slic3r.org) and PrusaSlicer (https://github.com/prusa3d/ PrusaSlicer). Open-source 3D printer operating firmware is another important facet of the RepRap project. The Marlin firmware (https://marlinfw.org) is designed to run on an Arduino Mega board and is compiled using the open-source Arduino IDE. siliconchip.com.au SPICE (Simulation Program with Integrated Circuit Emphasis) is opensource software for circuit simulation, developed at the University of California, Berkeley. It is very powerful but a little difficult to set up and use. Linear Technology’s GUI version, LTspice (siliconchip.au/link/ac2p), is not open source but it is free and it is popular because it is so easy to use, and comes with lots of builtin component models. Since LTspice only runs on Windows, Ngspice (https:// ngspice.sourceforge.io) is a free and open-source alternative that also runs on Linux, macOS and other operating systems. Amateur radio FreeDV (https://freedv.org & Fig.21) is a free and open-source digital voice app for SSB amateur radio. It can run on Windows, Linux and macOS. It is helping the transition from analog to digital voice modes of HF amateur SSB, the previous major Fig.20: a sample screen of OpenSCAD showing its scripting language; insert is a 3D printer modelled using OpenSCAD. Source: https://i.materialise.com/en/3ddesign-tools/openscad & https://github.com/martinbudden/BabyCube Australia's electronics magazine February 2025  19 Fig.21: a screenshot of the FreeDV digital voice app for SSB amateur radio. Source: https://freedv.org transition being from AM to SSB in the 1950s and 1960s. Unlike many other digital modes, the voice codec used by FreeDV is not proprietary and is also open source. It uses neural net speech coding (LPCNet) and provides 8kHz of audio bandwidth while using only 1.6kHz of RF bandwidth. It is thought to be the first use of such neural net speech encoding for real-world applications. MMANA-GAL (http://gal-ana.de/ basicmm/en) is an antenna design program that is free for non-commercial use but is copyrighted by the author, although the source code is available. WSTJ-X (https://wsjt.sourceforge. io/wsjtx.html & Fig.22) implements Fig.22: a sample screen from the WSTJ-X digital radio software. Source: https://wsjt.sourceforge.io/wsjtx.html several popular amateur radio digital modes such as FST4, FST4W, FT4, FT8, JT4, JT9, JT65, Q65, MSK144 and WSPR. It also has one called ECHO for detecting your own radio signals reflected from the moon when you try to ‘moon bounce’. It runs on Windows, macOS and Linux. Data Acquisition LDAQ (Lightweight Data Acquisition, https://github.com/ladisk/LDAQ & Fig.23), is a Python-based toolkit for data acquisition that is said to be powerful and user-friendly. It is intended for use by researchers, engineers or hobbyists. It works in all Python environments. Fig.23: a sample screenshot of the LDAQ data acquisition software. Source: https://github.com/ladisk/LDAQ/blob/master/docs/source/images/FRF_ visualization.gif 20 Silicon Chip Australia's electronics magazine OpenDAX (https://opendax.org) is an open-source framework to build parts of data acquisition systems such as distributed control systems (DCS), programmable logic controllers (PLCs) and supervisory control and data acquisition (SCADA) systems. The authors describe the software as not yet ready for mission-critical applications. Operating Systems Android is based on Linux (see below) and its basic implementation is open-source. We discussed some open-source versions of Android in our article on privacy phones (June 2024; siliconchip.au/Article/16280), GrapheneOS (https://grapheneos.org). FreeDOS (https://freedos.org) is an open source DOS-compatible operating system for IBM-PC compatible computers. It is intended for running legacy software and embedded systems. Microsoft has released the MS-DOS v1.25, v2.0 and v4.0 source code under an MIT license for others to view and experiment with. See https://github. com/microsoft/MS-DOS Open Network Linux and SONiC are open-source network operating systems (www.opennetlinux.org & https://sonicfoundation.dev). A commercial example (not open source) of a network operating system is Microsoft Windows Server. GNU (www.gnu.org) is a collection of hundreds of items of free software siliconchip.com.au that can be used as a Unix-like operating system or as parts of an operating system. It includes applications, libraries, developer tools and games. GNU is the original free software concept project by Richard Stallman, started in 1983, with software development starting in 1984 and the free software philosophy published as the GNU Manifesto in 1985 (www.gnu. org/gnu/manifesto.html). The release of the GNU suite was the first time an operating system could be run using free software. The completed GNU components (except for the kernel, the core part of an operating system) led to the independently created Linux operating system, developed by Linus Torvalds from 1991, which is now the main use for these GNU components. Linux is released under a GNU license, and the Linux kernel is what is most used with the GNU software components. According to GNU, Linux should be called GNU/Linux because it wouldn’t work without both sets of components (see www.gnu.org/gnu/linux-and-gnu. html). Linux is actually the name of the kernel of the Unix-like GNU operating system (created by Linus Torvalds), not the entire operating system itself. While it is certainly true that the Linux kernel would not exist without GNU’s tools, and that it relies on many of their libraries to be useful, we’re referring to it as Linux for brevity (it’s a somewhat controversial topic). Linux is an enormously popular alternative to commercial operating systems like Windows. It is available in around 1000 distributions (‘distros’), each tailored to particular uses or tastes, with different applications included. Some Linux distributions may contain commercial software, as Linux has commercial and industrial applications as well, but most distros contain free and open-source software. If you want to migrate to Linux, as I might do in the near future, you can try ‘live’ distros that you can install on a USB stick or other removable media without altering the data on your computer. Distros that can be used live include Debian, SUSE, Ubuntu (Fig.24), Linux Mint, MEPIS and Fedora Linux. Some distributions specifically for live use include Knoppix, Puppy Linux, Devil-Linux, SuperGamer, SliTaz Linux and dyne:bolic. As for which distribution to use, that would siliconchip.com.au Fig.24: an example of the Ubuntu Linux desktop. Source: www.dreamhost.com/ blog/linux-distros Fig.25: most of the world’s top supercomputers run some version of Linux, including the Summit supercomputer at Oak Ridge National Laboratory in the United States, which runs RHEL. Source: https://w.wiki/BsLo need a whole article in itself, however Ubuntu (https://ubuntu.com) is considered a good choice for beginners; it does come with some proprietary device drivers, although it is still free. Another distribution cited as being suitable for beginners, which is based on Ubuntu, is Linux Mint. Ubuntu, in turn, is based on Debian. Apart from home users, many scientific, commercial and industrial users employ Linux, including on supercomputers, the International Space Station and SpaceX vehicles (Dragon, Falcon 9 and Starship). Australia's electronics magazine You can watch a video explaining why one Windows user switched to Linux and the basics of Linux Mint at https://youtu.be/fDDtBKOqTKI Traditionally, supercomputers (Fig.25) ran proprietary operating systems. Today, most run some variant of Linux, such as Red Hat Enterprise Linux (RHEL). RHEL is a commercialised version of Linux but it is based on the free and open-source Fedora Linux and CentOS Stream versions of Linux. AlmaLinux (https://almalinux.org) is a FOSS substitute for RHEL. Some February 2025  21 supercomputers use other versions of Linux, such as Ubuntu. Development and back-end software Compared to the old days of paid compilers and software demos distributed on physical media, there is a lot of choice for people who want free software. Compilers & development software Git (https://git-scm.com) is a free & open-source distributed version control system that can be used for software development or any other time a set of text files will undergo many revisions, possibly by a team of people. Subversion or svn (https://subversion. apache.org) is another similar free & open-source tool that we use (because we find it easier than git). The GNU Compiler Collection (GCC, https://gcc.gnu.org) is a collection of free compilers for Ada, C, C++, D, FORTRAN, Go, Objective-C, Objective-C++ and Rust for various operating systems and computer architectures. GCC compilers are used for most GNU projects and for the Linux kernel, along with many other opensource projects. LLVM (www.llvm.org) and its frontend Clang is a compiler for C languagues (C, C++, CUDA etc). It also is the default compiler for macOS. Processing (https://processing.org) is a combined graphics library and integrated development environment intended for graphical programming. We used it for our LED Christmas Tree project in the December 2018 issue, but you will probably be more familiar with it as the basis for the Arduino IDE. Python (www.python.org) is a dynamically typed, high-level programming language that many people like because it is easy to learn and use but much more powerful than languages like BASIC. Like many modern programming languages, it is also an open-source project. MicroPython is a variant of it that runs on microcontroller boards like the Raspberry Pi Pico. Visual Studio Code (https://code. visualstudio.com) or VS Code is an open-source integrated development environment (IDE) released by Microsoft. It is based on their earlier proprietary Visual Studio program but can run in Windows, Linux, macOS or even a web browser. 22 Silicon Chip Databases MySQL (www.mysql.com) is a free and open-source relational database management system. It is available under either a free and open-source licence or a proprietary licence. PostgreSQL (www.postgresql. org) is a free and open-source relational database management system, which claims to be the world’s most advanced. We think PostgreSQL is very well designed and well worth looking into if you need a relational database. One of its most impressive features is that it supports most concurrency features without any locking, meaning it is almost immune to deadlocks, something that can be a real problem in other database systems. Instead, it uses a versioning system. This allows you to do things like take a ‘snapshot’ to back up the entire database while it is in active use! Web Content Management & Servers Apache (https://httpd.apache.org) is the “number one HTTP [web] server on the internet”, although it was recently overtaken in popularity by NGINX. Together, the two packages power over 60% of all web servers. Apache is one of the earlier opensource projects and, as such, even created its own class of open-source licence that is now used by other projects (the Apache license mentioned earlier). There is also Apache Tomcat (https://tomcat.apache.org), which is an ‘evolution’ of the Java EE (enterprise applications) platform. Drupal (www.drupal.org) is web content management software that is used by the US White House and 14% of the top 10,000 websites worldwide (see siliconchip.au/link/ac2q). WordPress (https://wordpress.org & Fig.26) is a very popular web content management system and blog software that is free and open-source. It is supported by about 60,000 (or more) plugins from other developers. Artificial intelligence There are quite a few open-source AI models and tools, although some AI models claimed to be open source do not meet accepted standards of opensource software. Open source models: ● Stable Diffusion (https://stability. ai/stable-image & Fig.27), which is free for non-commercial or limited commercial use. It generates images from a text description. ● The source code for GPT-2 is publicly available but the trained model and data is not (https://github.com/ openai/gpt-2). ● GPT-NeoX and GPT-J are pretrained language models. ● Llama by Meta (Facebook, www. llama.com) is listed as open-source and includes pre-trained models. It can be used for commercial applications but has restrictions around licensees with “greater than 700 million monthly active users in the preceding calendar month”. Open source libraries/frameworks: ● TensorFlow (www.tensorflow.org & Fig.28), a software library for deep learning and artificial intelligence. ● PyTorch (https://pytorch.org), a library for machine learning and Fig.26: WordPress has a large amount of pre-made themes that can be used to quickly create a website. Source: https://wordpress.com/themes Australia's electronics magazine siliconchip.com.au Fig.27: some example images generated by Stable Diffusion 3.5. Source: https://stability.ai/news/introducing-stablediffusion-3-5 deep learning for applications such as vision and natural language processing. ● Scikit-learn (https://scikit-learn. org/stable/), a machine-learning library for predictive data analysis. ● Hugging Face Transformers (https://github.com/huggingface/ transformers), a collection of models for text-based tasks such as answering questions, summarisation, image classification, object detection, speech recognition and audio classification. Open-source datasets: ● ImageNet (https://image-net.org), an image library for object recognition research. ● Common Crawl ‘crawls’ the web and stores the data in its archives (https://commoncrawl.org), which are made freely available to researchers and developers. It has stored 250 billion web pages over the last 17 years, with 3-5 billion pages added every month. This data can be used to train artificial intelligence models. Cluster & grid computing A computer cluster is a potentially very large collection of computers that are managed to act as a single large computer. Computer clusters are used for calculation-­intensive tasks such as scientific computing (eg, weather prediction, protein folding or fluid dynamics) rather than tasks with high input/ output requirements like databases. Most supercomputers these days use computer clusters. Grid computing utilises the capacity of numerous individual computers to perform individual parts of various computational tasks. The capacity utilised might be otherwise unused; ‘spare’ CPU cycles are ‘donated’ to a distributed computing project such as BOINC or SETI<at>home. Apache Mesos (https://mesos. apache.org) is software to manage computer clusters. Twitter used to use Apache Mesos, but now uses Kubernetes. A Beowulf Cluster is a supercomputer made from many inexpensive computers, generally running Linux and other free and open-source software such as Open MPI, a message passing interface, and Open Source Cluster Application Resources (OSCAR) high-performance computing management software. BOINC (Berkeley Open Infrastructure for Network Computing, https:// github.com/BOINC/boinc) is an opensource project to facilitate distributed grid computing projects. It was originally developed to manage SETI<at> home, which analyses radio telescope data via millions of PCs worldwide. It has now been expanded to other distributed computing projects in the areas of astrophysics, biology, environment, linguistics, mathematics, medicine and others. Kubernetes (https://kubernetes.io) is a containerised application management system that was originally SC authored by Google. Fig.28: an image (left) after applying 10 iterations of DeepDream (right) that was trained on dogs. DeepDream is implemented using TensorFlow. Source: user MartinThoma – https://w.wiki/5fek siliconchip.com.au Australia's electronics magazine February 2025  23