Alternative Operating Systems

I think it would be a good idea to list operating systems that have a certain amount of quality, longevity, and inertia (an arbitrary measurement system that I decide on the fly), and not at all developed from (though can be compatible with) any currently mainstream OS (Linux, BSD, Windows, macOS) code base.

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UNIX-like

  • SerenityOS

    • AMD64 compatibles

    • targeting virtual machines at the moment

    • all software is original to the system (no ports)

    • moves very quickly

  • Redox

    • microkernel

    • written in rust

    • copious documentation

    • AMD64

  • Fiwix

    • educational system

    • x86

  • Managarm

    • somewhat Linux compatible

    • fully async and microkernel

    • AMD64

    • moves quickly

  • 9front

    • fork/continuation of Plan9 from Bell Labs

    • i386, AMD64, ARM, ARM64, MIPS

  • ELKS

    • this one technically breaks my rules listed earlier

    • embeddable Linux kernel subset

    • 8086, 8088, 80188, 80186, 80286, NEC V20, V30

  • Open Indiana

    • continuation of Open Solaris

    • AMD64

    • built on Illumos

  • MINIX

    • microkernel

    • compatible with NetBSD

    • PC compatibles, Motorola 68000, SPARC, Atari ST, Commodore Amiga, Macintosh, SPARCstation, NS32532, ARM, Intel Management Engine

    • was originally a teaching OS by Andrew S. Tanenbaum

    • for post-2015 Intel chipsets, OS of the Intel Management Engine

  • ToaruOS

    • AMD64, VMWare, VirtualBox

    • moves quickly

AmigaOS-like

  • AmigaOS

    • the original is still being developed

  • MorphOS

    • 3D hardware acceleration

    • transparent execution of 68k binaries for Commodore Ax00

    • Macintosh PPC, AmigaOne 500, AmigaOne X5000

  • AROS

    • Amiga m68k, i386, AMD64, PPC, ARMHF

Similar to OS/2 or NT

  • ReactOS

    • Windows software and drivers

    • x86, AMD64

    • very slow moving

  • ArcaOS

    • developed from OS/2

    • x86 PC platform

  • GreenteaOS

    • fork of ReactOS aiming for more modern compatibility

  • osFree

    • open source OS/2 project

    • moves slowly

DOS-like

  • FreeDOS

    • runs almost all MS-DOS/PC-DOS software

    • 8088/8086, 386+ (non-UEFI)

  • P-DOS

    • x86, z-series mainframes

    • compatible with most MS-DOS/PC-DOS software on x86

OTHERS

  • HaikuOS

    • source-compatible with BeOS

    • x86, RISC-V, PPC, Sparc, ARM

    • slow-moving, but gaining some steam

  • C64OS

    • for the Commodore 64

    • guides, applications, utilities, and pre-installed SD are standard

  • OS/380

    • actually a family of 31-bit mainframe operating systems: MVS/380, VM/380 and VSE/380

    • mostly compatible with z/OS

  • RISCOS

    • ARM, especially RPi

    • continuation of Acorn’s RISC OS

    • moves slowly

  • PumpkinOS

    • continuing PalmOS but targeting x86 desktops

    • transparently runs 68k Palm binaries

  • TempleOS

    • AMD64

    • very unique

    • many forks on GitHub

    • requiescat in pace, Terry Davis

  • Kolibri OS

    • x86

    • fork of Menuet

    • fits on a floppy

  • MenuetOS

    • x86, AMD64

    • fits on a floppy

  • MikeOS

    • 8088/8086

    • educational system

    • many handbooks and tutorials to get into OSdev

  • Zeal

    • Z80

    • 6KB ROM, 1K RAM as minimum for the kernel

    • tons of documentation

    • moves at a moderate pace

  • Mezzano

    • written in Common LISP

    • currently targets VirtualBox and QEMU

    • moves slowly but it’s feature rich

  • Visopsys

    • x86

    • very good partitioning tool

    • slow moving