- FreeDOS [GNU GPL]
- FreeDOS-32 [GNU GPL]
- ReactOS [GNU GPL]
- Visopsys [GNU GPL]
Misspellings: iperating, kperating, lperating, pperating, 0perating, 9perating, ooerating, olerating, o-erating, o0erating, opwrating, opsrating, opdrating, oprrating, op4rating, op3rating, opeeating, opedating, opefating, opetating, ope5ating, ope4ating, operzting, opersting, operwting, operqting, operaring, operafing, operaging, operaying, opera6ing, opera5ing, operatung, operatjng, operatkng, operatong, operat9ng, operat8ng, operatibg, operatimg, operatijg, operatihg, operatinf, operatinv, operatinb, operatinh, operatiny, operatint, perating, oerating, oprating, opeating, operting, operaing, operatng, operatig, operatin, poerating, oeprating, opreating, opearting, opertaing, operaitng, operatnig, operatign, ooperating, opperating, opeerating, operrating, operaating, operatting, operatiing, operatinng, operatingg, aystems, zystems, xystems, dystems, eystems, wystems, ststems, sgstems, shstems, sustems, s7stems, s6stems, syatems, syztems, syxtems, sydtems, syetems, sywtems, sysrems, sysfems, sysgems, sysyems, sys6ems, sys5ems, systwms, systsms, systdms, systrms, syst4ms, syst3ms, systens, systeks, systejs, systema, systemz, systemx, systemd, systeme, systemw, ystems, sstems, sytems, sysems, systms, systes, system, ysstems, ssytems, sytsems, sysetms, systmes, systesm, ssystems, syystems, sysstems, systtems, systeems, systemms, systemss