Digital supported three operating systems on Alpha: OpenVMS, DEC OSF/1 (renamed Digital UNIX and then Tru64 UNIX), and Microsoft Windows NT. Linux, NetBSD, and OpenBSD are still maintained on Alpha; FreeBSD dropped Alpha in 7.0. Current Linux distributions for Alpha are listed on Distributions.

Which of these a system can run depends mostly on its firmware:

OpenVMS, Tru64 UNIX, and the BSDs boot only from the SRM console; ⁷⁾ systems without SRM, such as the Alpha XL and XLT, can run only Windows NT and Linux (with MILO). ⁸⁾ The SRM console for evaluation boards and OEM motherboards was licensed separately (see SRM licensing).

The tables summarize which operating systems each system supported. "Unofficial" means that the operating system ran but was not supported by its vendor. A blank cell means that no source has been found.

The Linux column follows the platforms in arch/alpha in Linux 6.10 and earlier. ^{9) 10)} "Linux 6.9 and earlier" means that Linux 6.9 was the last version to support the system. "Untested" means that current kernels include support, but no one has reported booting a current kernel on the system. "MILO only" marks systems without SRM, which must boot Linux with MILO. Systems sold with AlphaBIOS that also have SRM, such as the Digital Server and the Personal Workstation a series, boot Linux after switching to SRM (see ARC Firmware: Switching to SRM).

"21164A only" means that Linux 6.10 and later require an EV56 (21164A) or later processor, so versions of the system with an older processor were last supported by Linux 6.9 (see Current Status). ¹¹⁾ Where the table names models, those are the models documented with a 21164A; the sources are on the pages for each system. ¹²⁾

• DEC 3000, DEC 4000, and DEC 7000: the kernel has no support for these systems, before or after Linux 6.10. ¹³⁾
• AlphaServer 8200, 8400, GS60, and GS140 (TurboLaser): the kernel has no support for these systems, before or after Linux 6.10. ^{14) 15)}
• Systems and processors removed in Linux 6.10: the Jensen, all EV4 and EV45 systems, the EB164, and any system fitted with an EV5 (21164) rather than an EV56 (21164A); see Linux.

Linux runs on most Alpha systems, booting from SRM with aboot or from ARC, AlphaBIOS, or ARCSBIOS with MILO. Systems without SRM, such as the Alpha XLT and the Ruffian, need MILO, ¹⁶⁾ and a current kernel needs a MILO built from the alphalinux repository; see MILO and Boot Loaders. Current distributions are listed on Distributions, and the installation procedure is described in Installation. Alpha/Linux can also be run without Alpha hardware under QEMU.

Linux 6.10 removed support for processors without the BWX extension (the EV4, EV45, and EV5 generations) and for the systems that can only use them. ¹⁷⁾ The removed systems are:

• the Jensen (DEC 2000 AXP and DECpc AXP 150), ¹⁸⁾
• all systems with the LCA processors or the APECS chipset: the AlphaStation 200, 250, 255, and 400 and AlphaServer 300 and 400 (Avanti), the Alpha XL, the Multia and AXPpci 33 (Noname), the AlphaBook 1, the Platform 2000, the EB64+, EB66, EB66+, and AlphaPC 64, and the EV4 versions of the AlphaServer 1000 and 1000A, ¹⁹⁾
• the EV4 and EV45 versions of the AlphaServer 2000 and 2100, and the AlphaServer 2100A (Lynx), ²⁰⁾
• the EB164, which only supports EV5 processors. ²¹⁾

Systems sold with both EV5 and EV56 processors, such as the AlphaStation 500 and the AlphaServer 1000, are still supported in their EV56 models. ²²⁾

The Titan (AlphaServer DS15, DS25, and ES45), Wildfire (GS80, GS160, and GS320), and Marvel (ES47, ES80, and GS1280) systems need kernels built without CONFIG_ALPHA_LEGACY_START_ADDRESS, which make defconfig enables; see Kernel. ^{23) 24)}

NetBSD and OpenBSD boot only from the SRM console, because they use the OSF/1 PALcode and cannot use the PALcode that ARC and AlphaBIOS provide. ²⁵⁾ There is no BSD equivalent of MILO. ²⁶⁾

NetBSD/alpha is the oldest of the BSD ports to Alpha. ²⁷⁾ It is still maintained, and its port-alpha@netbsd.org mailing list remains active. Alpha is supported in NetBSD 11.0 (30 July 2026) and 10.2. ²⁸⁾ Install images are published for each release, such as NetBSD-11.0-alpha.iso. ²⁹⁾ NetBSD also runs under QEMU; see Emulators. The supported systems are listed on the NetBSD/alpha port page.

FreeBSD 6.x was the last series to support Alpha, which was removed in FreeBSD 7.0. ³⁰⁾

OpenBSD/alpha is still supported, including SMP, in the current release, OpenBSD 7.9 (19 May 2026). ³¹⁾ The installation media are install79.iso and cd79.iso, and the procedure is described in the release's INSTALL.alpha. ³²⁾ The supported systems are listed on the OpenBSD/alpha page.

Windows NT ran on Alpha from version 3.1 ³³⁾ and needs ARC or AlphaBIOS firmware. Digital Semiconductor's evaluation boards and OEM motherboards shipped with this firmware and supported Windows NT 3.51 and 4.0. ³⁴⁾

Compaq ended Windows NT development for Alpha in August 1999. ³⁵⁾ Windows NT 4.0 was the last released version; Windows 2000 for Alpha reached only prerelease builds, up to at least Release Candidate 1. ³⁶⁾ The last Windows NT firmware was AlphaBIOS V5.71, for the AlphaServer DS10, AlphaStation XP900, and AlphaServer DS20 and DS20E. ³⁷⁾ On systems with both consoles, Linux is booted from SRM; see Firmware. ES40-Emu runs Windows NT and Windows 2000 for Alpha; see Emulators.

The first OpenVMS for Alpha was OpenVMS AXP. The DEC 2000 was added with OpenVMS AXP V1.5-1H1, a limited hardware release. ³⁸⁾ Later systems required later versions.

From at least 1998, OpenVMS was licensed for non-commercial use through the OpenVMS Hobbyist program run with DECUS. ^{39) 40)}

In July 2014 HP named VMS Software Inc. (VSI) the exclusive developer of future versions of OpenVMS, and licensed it the source code. ⁴¹⁾ VSI's releases for Alpha are OpenVMS V8.4-2L1 and V8.4-2L2; V8.4-2L2 is built for EV6 and later processors, so older systems need V8.4-2L1. ⁴²⁾ VSI offers standard support for both through 2035. ⁴³⁾ OpenVMS does not run under QEMU, but several other emulators run it; see Emulators.

Digital's UNIX for Alpha was called DEC OSF/1 until 1995, when it was renamed Digital UNIX, ⁴⁴⁾ and Compaq renamed it Tru64 UNIX in 1999. ⁴⁵⁾ Its releases, hardware requirements, licensing, and end of support are described in Tru64 UNIX.

Linux can share a machine with OpenVMS or Tru64 UNIX, since all of them boot from the SRM console. One arrangement is to install each system on its own disk, make Linux the default with bootdef_dev, boot_file, and boot_osflags, and boot the other system by naming its disk, for example boot -file vmunix -flags a dka0 for Tru64 UNIX. ⁴⁶⁾ Adding a disk can change the names that Linux gives to the disks already present, so that the kernel no longer finds its root file system; ⁴⁷⁾ referring to file systems by UUID or label rather than by device name avoids this. With an initramfs that supports it, such as Debian's, the root file system can be given as root=LABEL=name in aboot.conf, and /etc/fstab can use LABEL= entries. ⁴⁸⁾ The kernel alone cannot do this on a BSD disklabel: without an initramfs, root= accepts a partition UUID or label only from GPT or MS-DOS partition tables. ⁴⁹⁾

NetBSD and OpenBSD also boot only from SRM (see BSD), so they can share a machine with Linux in the same way, each on its own disk.

A disk labeled by Tru64 UNIX can also hold aboot. Its whole-disk c partition does no harm, but an installer may refuse to write the boot block because no space lies outside the partitions, and swriteboot -f then writes it by hand. ⁵⁰⁾

OpenVMS, Tru64 UNIX, and ARC each keep the time-of-year clock relative to a different epoch; see SRM Console: Known issues.

Linux reads the BSD-style disk label that Tru64 UNIX writes, through its OSF partition support (CONFIG_OSF_PARTITION), which is enabled by default on Alpha. Partition a of the label appears as partition 1, b as 2, and so on. ^{51) 52)}

The kernel's ufs driver reads UFS file systems. It cannot detect which variant of UFS a file system is, so the variant is given with the ufstype mount option; the default is old, and 44bsd is the variant used by NetBSD and OpenBSD. Write support (CONFIG_UFS_FS_WRITE) is experimental. ^{53) 54)} Digital UNIX UFS file systems have been mounted with ufstype=old, ⁵⁵⁾ and NetBSD/alpha file systems with ufstype=44bsd, read-only. ⁵⁶⁾

Linux has no driver for AdvFS, the other file system of Tru64 UNIX, ⁵⁷⁾ or for the OpenVMS file systems ODS-2 and ODS-5. ⁵⁸⁾ HP released the AdvFS source code under the GPLv2 in June 2008, but not as a working Linux port. ⁵⁹⁾ Archives made on Tru64 UNIX with tar, pax, or cpio can be read on Linux, but vdump archives cannot; see Tru64 UNIX.

Linux on Alpha began at Digital, before any of the Alpha/Linux mailing lists existed, with a 32-bit kernel on the Jensen, followed by the Avanti. ⁶⁰⁾ The Jensen booted Linux from SRM, since no evaluation board PALcode was ever available for it. ⁶¹⁾ Jim Paradis of Digital's Alpha Migration Tools Group described the work in a "Linux/AXP Progress Report", dated 9 September 1994: a port of the Linux 1.0 kernel that kept every kernel data type to 32 bits except where the kernel met the hardware, so that code such as the file systems would work unmodified. It was cross-developed on a DEC 3000 running DEC OSF/1, with the kernel debugged under Digital's ISP simulator, and its drivers used the console callbacks. ⁶²⁾

By November 1994 the port, renamed Linux/Alpha in keeping with Digital's policy, ran from the hard disk. ⁶³⁾ The Linux/Alpha Software Developers' Kit, the first public release of Linux components for Alpha, followed on 23 January 1995. It was cross-compiled from another host and had only console-callback drivers. ⁶⁴⁾

BLADE 0.1 (Basic Linux/Alpha Distribution Eyesore), released on 1 July 1995, was the first Alpha/Linux distribution that could be installed without a second machine. It was a set of floppy images for the AXPpci 33 (Noname), built on a 1.2.8 kernel, and was 64-bit, the port having moved to 64 bits in the meantime. ⁶⁵⁾

HP officially supported Red Hat Linux 7.2 for Alpha on the AlphaServer DS10, DS20, ES40, and ES45. ⁶⁶⁾ The DS25 and ES45 firmware release notes list Red Hat Linux 7.2 among the supported operating systems. ^{67) 68)}

The following sources conflict with each other or with the account given above. They are listed here for further investigation.

• OpenVMS on the EB164
  • Digital Semiconductor 21164 Alpha Microprocessor Motherboard User's Manual, p. 3-10: "The EB164 does not support the OpenVMS operating system."
  • Alpha SRM Console for Alpha Microprocessor Motherboards User's Guide, p. vii, describes its SRM console for boards "running the DIGITAL UNIX and OpenVMS operating systems", including the EB164.
• OpenVMS on the Multia
  • "Re: digital unix libs", Jay Estabrook, axp-list, 1 Oct 1996: "VMS does NOT run on the UDB!"
  • "Re: Multia/UDB Comments", Mihaly HOMONNAI, axp-list, 20 Jun 1996: "it is possible to run OVMS on Multias."
• Tru64 UNIX on the UP2000
  • UP1000 Spec Sheet, January 2000, p. 2, lists "Tru64 UNIX" among the UP2000's supported operating systems.
  • "RE: UP2000 and Tru64?", Mike Foley, axp-list, 23 Dec 1999: "The UP2000 is not a officially supported platform for running Tru64."
• Tru64 UNIX on the CS20
  • "Re: DS20L", Rich Payne, axp-list, 30 May 2002: "Tru64 ran on the CS20 from day 1, though it wouldn't use the onboard SCSI controller."
  • "Re: DS20L", Maurice Hilarius, axp-list, 30 May 2002: the CS20 "could not run TRU64."
• Windows NT on the ES40
  • FWREADME.TXT for the ES40 on the V7.3 firmware CD lists AlphaBIOS V5.71.
  • Alpha Systems Firmware Update V7.3 Release Notes Overview, p. 10, lists no Windows NT firmware for the ES40.
• Windows NT on the XP900
  • Alpha Systems Firmware Update V7.3 Release Notes Overview, p. 10, lists AlphaBIOS V5.71 for the "DS10, AlphaStation XP900".
  • AlphaStation XP900, Systems and Options Catalog, September 1999: "available in a Desktop configuration with either Compaq's Tru64 UNIX, OpenVMS, or LINUX-ready (operating-system less)."
• Windows NT on the DS10
  • Compaq AlphaServer DS10, June 1999, p. 6: "Operating Systems Tru64 UNIX 4.0F, OpenVMS 7.1-2, Windows NT, Linux"
  • "RE: UP2000", KirkE@paccessglobal.com, axp-list, 28 Feb 2001: "I don't think DS10/DS10L ever supported NT (at least publicly), I've never seen an AlphaBIOS for either of them."
• Last Tru64 UNIX release for older systems
  • "end of life for DEC branded Alphas (and Tru64)", William H. Magill, axp-list, 20 Sep 2000, forwards Tom Blinn: "V5.1 is the last release that will support the older "DEC" branded Alpha systems (the ones that do NOT have PCI buses for I/O"
  • The same message summarizes this as "any EV56 or earlier processor will no longer be supported by Tru64 after 5.1".
  • "SUMMARY: DEC3000 300s and DEC 3000 400s with Tru64 v5", Robert Bannocks, tru64-unix-managers, 30 Jan 2003: "It seems that the last supported version was 5.0A. 5.1 will run although it it NOT suupported."
  • "Re: [gentoo-alpha] Gentoo on a DEC3000/300LX?", Aron Griffis, gentoo-alpha, 11 Mar 2003: "versions up to V5.1A included support for the 3000, I believe".