Wine is animplementationof the WindowsAPI on top of Xand Unix. Itdoes notrequireMicrosoftWindows, butcan use nativeWindows DLLs ifthey areavailable. Itprovides both adevelopmenttoolkit forporting Windowssource code toUnix as well asa programloader,allowing manyunmodifiedWindowsprograms to runon x86-basedUnixes.
Fiwix is anoperatingsystem kernelwritten fromscratch, basedon the UNIXarchitectureand fullyfocused onbeing POSIXcompatible. Itis designed anddevelopedmainly as ahobby OS and,since it servesalso foreducationalpurposes, thekernel code iskept as simpleas possible forthe benefit ofreaders orstudents. Itruns on thei386 hardwareplatform and iscompatible witha good base ofexisting GNUapplications.
IPFire is aLinux firewalldistributionthat is builtfrom source andcomes with lotsof additionalfeatures. It iseasy to set upand administer.It features afirewall withstatefulinspection, acontentfilteringengine, trafficcontrol (QoS),VPN technology,and a lot oflogging.
The OpenBSDprojectproduces afree,multi-platform4.4BSD-derivedUNIX-likeoperatingsystem.Emphasizingportability,standardization,coherency,correctness,proactivesecurity andintegratedcryptography.It comes withalmost 9000softwarepackage in itsports,including acustom X11environment(Xenocara),desktopenvironments,web andmultimediaapplications,compilers andprogramminglanguages. Italso harbourstheOpenBSD-maintainedsoftwareprojectsOpenSSH,LibreSSL,OpenIKED,OpenBGPD
ReactOS is afree and opensourceoperatingsystem writtenfrom scratch.It'sdesign is basedon Windows inthe same wayLinux is basedon Unix,however ReactOSis not Linux.ReactOS looksand feels likeWindows, isable to yourrun Windowssoftware andyour Windowsdrivers, and isfamiliar forWindows users.
FreeDOS is acomplete, free,DOS-compatibleoperatingsystem that youcan use to playclassic DOSgames, runlegacy businesssoftware, ordevelopembeddedsystems. Anyprogram thatworks on MS-DOSshould also runon FreeDOS. Itdoesn’t costanything todownload anduse FreeDOS.You can alsoshare FreeDOSfor others toenjoy! And youcan view andedit our sourcecode, becauseall FreeDOSprograms aredistributedunder the GNUGeneral PublicLicense or asimilar opensource softwarelicense.
MikeOS is anoperatingsystem for x86PCs, written inassemblylanguage. It isa learning toolto show howsimple 16-bit,real-mode OSeswork, withwell-commentedcode andextensivedocumentation.It features atext-modedialog and menudriveninterface, aBASICinterpreter,severalthird-partyprograms andthe ability toboot from afloppy disk,CD-ROM or USBkey.
ZShaolinunleashes thepower ofGNU/Linux onyour Androidphone or tabletby installing asmall andpowerful shellenvironment. It comes withapplications toedit images,audio and videousing batchscripts one canwrite andupload. It doesnot requirerooting, noteven anInternetconnection towork.
HelenOS is amicrokernel-basedoperatingsystem writtencompletely fromscratch. It isnot UNIX-likeand does notimitate anyother OS. Itruns on 7different CPUarchitectures(IA-32, AMD-64,ARM, MIPS,PowerPC, SPARC,Itanium),supports SMP,networking,USB, sound andhas its ownoriginal GUI.
CentOS is anenterpriseLinuxdistributionbased on thesources fromRed HatEnterpriseLinux. CentOSconforms withRed Hat'sredistributionpolicy and aimsto be 100%binarycompatible.Each CentOSversion issupported for10 years (bymeans ofsecurityupdates). A newCentOS versionis releasedevery 2 yearsand each CentOSversion isregularlyupdated (every6 months) tosupport newerhardware.