DECstation
The DECstation was a brand of computers used by DEC, and refers to three distinct lines of computer systems—the first released in 1978 as a word processing system, and the latter two both released in 1989. These comprised a range of computer workstations based on the MIPS architecture and a range of PC compatibles. The MIPS-based workstations ran ULTRIX, a DEC-proprietary version of UNIX, and early releases of OSF/1.
DECstation 78
The first line of computer systems given the DECstation name were word processing systems based on the PDP-8. Thesesystems, built into a VT52 terminal, were also known as the VT78.
DECstation RISC workstations
History
The second line of DECstations began with the DECstation 3100, released on 11 January 1989 as the first commercially available RISC-based machine built by DEC.By the late 1980s, Unix RISC vendors like Sun Microsystems lured many customers from DEC's traditional CISC VAX systems. The company recognized the threat of RISC's two-to-one price/performance ratio advantage over VAX. DECstation 3100 was among several internal projects competing to be its response.
This line of DECstations was from an advanced development skunkworks project carried out in DEC's Palo Alto Hamilton Avenue facility. Known as the PMAX project, its focus was to produce a computer systems family with the economics and performance to compete against the likes of Sun and other RISC-based Unix platforms. The brainchild of James Billmaier, Mario Pagliaro, Armando Stettner, and Joseph DiNucci, the systems family was to also employ a third party RISC architecture instead of the CISC VAX or the then still-under-development PRISM architectures.
After considering Intel i860, Motorola 88000, and others, the group quickly selected the MIPS line of microprocessors. The MIPS microprocessors supported both big- and little-endian modes. Little-endian mode was chosen both to match the byte ordering of VAX-based systems and the growing number of Intel-based PCs and computers. In contrast to the VAX and the later DEC Alpha architectures, the DECstation 3100 and family were specifically designed and built to run a UNIX system, ULTRIX, so MIPS's incompatibility with VAX and its VMS operating system was not a problem.
DEC sold more than $1 billion of DECstations in 1989. The 3100 was indeed substantially faster than VAX; citing RISC's "at least a two-to-one performance advantage", the 3100 designers wrote that they had built "the machine that we ourselves had wanted for a very long time". At launch it was the price/performance leader, with its MSRP or about $850/million instructions per second, about 40% less than the comparable Sun system. The press expected that DECstation, and comparable products from others, would greatly increase customers moving from traditional minicomputers to RISC. One of the issues being debated at the project's inception was whether or not DEC could sustain, grow, and compete with an architecture it did not invent or own. As the core advocates later left the company, the MIPS-based line of computers was shut down in favor of the Alpha-based computers, a DEC invented and owned architecture, descended from the PRISM development work.
The first generation of commercially marketed DEC Alpha systems, the DEC 3000 AXP series, were similar in some respects to contemporaneous MIPS-based DECstations, which were sold alongside the Alpha systems as the DECstation line was gradually phased out. Both used the TURBOchannel expansion bus for video and network cards, as well as being sold with the same TURBOchannel option modules, mice, monitors, and keyboards.
Later DECstations planned to be based on the ECL-based R6000 were canceled on 14 August 1990 after Bipolar Integrated Technology failed to deliver sufficient volumes of the microprocessor, which was difficult to fabricate. Yields of the R6000 were further reduced as DEC required the little-endian mode used from the beginning to continue to be available.
The MIPS-based DECstations were used as the first target system and development platform for the Mach microkernel, as well as early development of the Windows NT operating system. More recently, various free operating systems such as NetBSD and Linux/MIPS have been ported to the MIPS-based DECstations, extending their useful life by providing a modern operating system.
DEC originally planned to introduce OSF/1 as its chosen Unix product, starting with a 1.0 version in March 1992 that promised to offer several enhancements over ULTRIX, albeit with some deficiencies that were meant to be fixed in a 2.0 version scheduled for the summer of that year. However, during a period of strategic uncertainty only weeks later in 1992, DEC appeared to abandon plans to officially provide OSF/1 on MIPS-based DECstations, instead re-emphasising ULTRIX for these models whilst intending to offer OSF/1 for the company's impending Alpha-based product lines. At this time, the DECstation 2100, 3100, 3100S, 5000/120, 5000/125 and 5000/200 models were stated as being able to run OSF/1, along with certain DECsystem models.
User dissatisfaction with the decision, driven by uncertainty about the future of the MIPS-based DECstations and ULTRIX, led to a revision of the company's strategy, with DEC promising "a production-quality version of OSF/1" with support for all of the company's Unix-based workstations and servers. Following on from the "advanced developer's kit" - this being the version offering support for only certain models - the intention was to produce an "end-user release" of OSF/1 during 1993 for R2000-, R3000- and R4000-based models, offering compatibility with OSF/1 on Alpha. Alongside such plans, DEC would also continue to support ULTRIX on its R4000-based systems. The strategic confusion was blamed on power struggles within DEC, with the decision made to abandon further OSF/1 work on DECstations being attributed to an executive having gained control over the Unix workstation group, thus reportedly causing "as much of an internal uproar as it did an external one". DEC later announced a detailed schedule for ULTRIX and OSF/1 releases that would deliver a 1.2 release on MIPS R3000 and R4000 machines in the summer of 1993, leading to synchronised 2.0 releases for MIPS and Alpha in the winter of 1993.
At the end of 1992, company representatives were once again less certain about the prospects of delivering OSF/1 on the DECstation range, with the projected release in the first half of 1993 "up in the air" and under threat of being cancelled if sufficient interest were not forthcoming from software vendors. Internally, the marketing group for the DECstation had been able to convince DEC's product strategy group that the loss in sales in failing to offer OSF/1 on the hardware would exceed the research and development costs involved in making it available, but company-wide spending cuts threatened such projects. Subsequent indications from DEC confirmed, without further elaboration, the cancellation of the product alongside increasing uncertainty around further hardware upgrades to the DECstation range beyond the planned R4400-based products. Shortly prior to the release of the DEC Alpha systems, a port of OSF/1 to the DECstation was completed, but it was not commercially released.
As the previously announced strategy had "fizzled", DEC representatives had reportedly "informed ULTRIX customers that they should start planning to move to Alpha workstations running OSF/1 in 1993", having the effect of undermining customer confidence in both the DECstation line and in ULTRIX, but also raising more serious concerns about the company's broader Unix strategy. Some customers, facing a migration to a new operating system on a new architecture, simply chose to migrate to competing Unix platforms instead.
Although introduced before DEC started to pursue a strategy based on the Advanced Computing Environment platform, the company's stated intention was that DECstation users could potentially migrate to an OSF/1-based product, potentially delivered in the form of SCO Open Desktop for the platform, offering binary compatibility with the existing ULTRIX system. DEC even suggested that Windows NT would be available for DECstation models, and Microsoft demonstrated NT running on Personal DECstation models. However, throughout the lifespan of the Alpha design activity, it had long been envisaged that VAX and MIPS binaries would be made to run on Alpha systems, leading to the development of the mx binary translator to run ULTRIX MIPS program images on Alpha-based DEC OSF/1 systems.
The GXemul project emulates several of these DECstation models.
Models
The original MIPS-based DECstation 3100 was followed by a cost reduced 2100. The DECstation 3100 was claimed to be the world's fastest UNIX workstation at the time. When it was introduced it was about three times as fast as the VAXstation 3100 which was introduced at about the same time. Server configurations of DECstation models, distributed without a framebuffer or a graphics accelerator, both Turbochannel and Q-bus based, were called "DECsystem" but should not be confused with some PDP-10 machines of the same name.Early models of the DECstation were heavily integrated systems with little expansion capability and do not even possess expansion buses. The DECstation 5000 systems, introduced later, improved on the lack of expansion capabilities by providing the TURBOchannel Interconnect. The DECstation 5000 systems are also ARC compatible. The last DECstation models focused on increased component integration by using more custom ASICs to reduce the number of discrete components. This began with the DECstation 5000 Model 240, which replaced discrete components with LSI ASICs and ended with the last model, the DECstation 5000 Model 260, which used a single VLSI ASIC for much of the control logic.
Packaged DECstation 5000 systems were sometimes suffixed with two or three letters. These letters refer to what graphics option the system has.