DEC Ultrix Опералық Жүйесінің Тарихы

Series of discontinued Unix operating systems by DEC

Ultrix (officially all caps ULTRIX) is the brand name of Digital Equipment Corporation's (DEC) discontinued native Unix operating systems for the PDP 11, VAX, MicroVAX and DECstations.

The initial development of Unix occurred on DEC equipment, notably DEC PDP 7 and PDP 11 (Programmable Data Processor) systems. Later DEC computers, such as their VAX, also offered Unix. The first port to VAX, UNIX/32V, was finished in 1978, not long after the October 1977 announcement of the VAX, for which – at that time – DEC only supplied its own proprietary operating system, VMS. DEC's Unix Engineering Group (UEG) was started by Bill Munson with Jerry Brenner and Fred Canter, both from DEC's Customer Service Engineering group, Bill Shannon (from Case Western Reserve University), and Armando Stettner (from Bell Labs). Other later members of UEG included Joel Magid, Bill Doll, and Jim Barclay recruited from DEC's marketing and product management groups. Under Canter's direction, UEG released V7M, a modified version of Unix 7th Edition (q. v.). In 1988 The New York Times reported that Ultrix was POSIX compliant. significant work for hardware error recovery, and many device drivers. Much work was put into producing a release that would reliably bootstrap from many tape drives or disk drives. V7M was well respected in the Unix community. UEG evolved into the group that later developed Ultrix.

The first native VAX UNIX product from DEC was Ultrix 32, based on 4.2BSD with some non kernel features from System V, and was released in June 1984. Ultrix 32 was primarily the brainchild of Armando Stettner. It provided a Berkley based native VAX Unix on a broad array of hardware configurations without the need to access kernel sources. A further goal was to enable better support by DEC's field software and systems support engineers through better hardware support, system messages, and documentation. It also incorporated several modifications and scripts from Usenet/UUCP experience. Later, Ultrix 32 incorporated support for DECnet and other proprietary DEC protocols such as LAT. It did not support VAXclustering. Given Western Electric/AT&T Unix licensing, DEC (and others) were restricted to selling binary only licenses. A significant part of the engineering work was in making the systems relatively flexible and configurable despite their binary only nature. DEC provided Ultrix on three platforms: PDP 11 minicomputers (where Ultrix was one of many available operating systems from DEC), VAX based computers (where Ultrix was one of two primary OS choices) and the Ultrix only DECstation workstations and DECsystem servers. Note that the DECstation and the later DECsystem products (as opposed to DEC's original DECsystem line) used MIPS processors and predate the much later Alpha based systems.

The V7m product was later renamed to Ultrix 11 to establish the family with Ultrix 32, but as the PDP 11 faded from view Ultrix 32 became known simply as Ultrix. When the MIPS versions of Ultrix was released, the VAX and MIPS versions were referred to as VAX/ULTRIX and RISC/ULTRIX respectively. Much engineering emphasis was placed on supportability and reliable operations including continued work on CPU and device driver support (which was, for the most part, also sent to UC Berkeley), hardware failure support and recovery with enhancement to error message text, documentation, and general work at both the kernel and systems program levels. Later Ultrix 32 incorporated some features from 4.3BSD and optionally included DECnet and SNA in addition to the standard TCP/IP, and both the SMTP and DEC's Mail 11 protocols. Notably, Ultrix implemented the inter process communication (IPC) facilities found in System V (named pipes, messages, semaphores, and shared memory). While the converged Unix from the Sun and AT&T alliance (that spawned the Open Software Foundation or OSF), released late 1986, put BSD features into System V, DEC, as described in Stettner's original Ultrix plans, took the best from System V and added it to a BSD base. Originally, on the VAX workstations, Ultrix 32 had a desktop environment called UWS, Ultrix Worksystem Software, which was based on X10 and the Ultrix Window Manager. Later, the widespread version 11 of the X Window System (X11) was added, using a window manager and widget toolkit named XUI (X User Interface), which was also used on VMS releases of the time. Eventually Ultrix also provided the Motif toolkit and Motif Window Manager. Ultrix ran on multiprocessor systems from both the VAX and DECsystem families. Ultrix 32 supported SCSI disks and tapes and also proprietary Digital Storage Systems Interconnect and CI peripherals employing DEC's Mass Storage Control Protocol, although lacking the OpenVMS distributed lock manager it did not support concurrent access from multiple Ultrix systems. DEC also released a combination hardware and software product named Prestoserv which accelerated NFS file serving to allow better performance for diskless workstations to communicate to a file serving Ultrix host. The kernel supported symmetric multiprocessing while not being fully multithreaded based upon pre Ultrix work by Armando Stettner and earlier work by George H. Goble at Purdue University. As such, there was liberal use of locking and some tasks could only be done by particular CPUs (e. g. the processing of interrupts). This was not uncommon in other SMP implementations of that time (e. g. SunOS). Also, Ultrix was slow to support many then new or emerging Unix system capabilities found on competing Unix systems (e. g. it never supported shared libraries or dynamically linked executables); and a delay in implementing bind, 4.3BSD system calls and libraries. The absence of memory mapped file support was regarded as a particular deficiency with Ultrix in comparison to its competitors in the early 1990s.

As part of its commitment to the OSF, Armando Stettner went to DEC's Cambridge Research Labs to work on the port of OSF/1 to DEC's RISC based DECstation 3100 workstation. This was released in 1991 with a Mach based kernel for the MIPS architecture. A port of Ultrix to Alpha was carried out during the initial development of the Alpha architecture, but was never released as a product. Later, DEC replaced Ultrix with OSF/1 on Alpha, ending Unix development on the MIPS and VAX platforms. The last major release of Ultrix was version 4.5 in 1995, which supported all previously supported DECstations and VAXen. There were some subsequent Y2K patches.