Tru64 UNIX 5.1B

Tru64, formerly Digital UNIX, formerly OSF/1 was DEC's UNIX product for their line of Alpha based systems. After DEC's acquisition by Compaq, it was renamed to Tru64. DEC previously had sold a BSD derivative named Ultrix for Vax and MIPS based systems. Their new UNIX on Alpha was meant to counter AT&T and Sun's SVR4 Unix. Tru64 / DIGITAL UNIX / OSF/1 is somewhat interesting in that it used portions of the Mach microkernel and BSD kernel and userland in a manner not entirely unlike NeXTSTEP or Mac OS X. Like OS X, Tru64 itself is not a microkernel system but uses Mach code in its kernel to implement threading and scheduling and possibly other features.

Release notes

Changes from 5.1A: Big Pages; IPv6 Enhancements; Netscape 6; Unicode 3.1

Product type
Release date
Minimum CPU
DEC Alpha
User interface
Download count
13 (9 for release)


Download name Version Language Architecture File size Downloads
Tru64 UNIX 5.1B - Disk 1 Operating System [DEC Alpha] 5.1B English 312.83MB 1
Tru64 UNIX 5.1B - Disk 2 Associated Products Volume 1 [DEC Alpha] 5.1B English 545.42MB 2
Tru64 UNIX 5.1B - Disk 3 Associated Products Volume 2 [DEC Alpha] 5.1B English 351.08MB 1
Tru64 UNIX 5.1B - Disk 4 Sources For Open Source Components [DEC Alpha] 5.1B English 180.46MB 1
Tru64 UNIX 5.1B - Disk 5 Patch Kit 4 [DEC Alpha] 5.1B English 170.98MB 1
Tru64 UNIX 5.1B - Disk 6 New Hardware Delivery [DEC Alpha] 5.1B English 355.34MB 1
Tru64 UNIX 5.1B - Disk 7 Firmware Update v6.8 [DEC Alpha] 5.1B English 205.23MB 2


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