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 (more widely known) 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. These systems, built into a VT52 terminal, were also known as the VT78.
DECstation RISC workstations
History
The second (and completely unrelated) line of DECstations began with the DECstation 3100, which was released on 11 January 1989. The DECstation 3100 was the first commercially available RISC-based machine built by DEC.
This line of DECstations was the fruit of an advanced development skunkworks project carried out in DEC's Palo Alto Hamilton Ave 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 Microsystems and other RISC-based UNIX platforms of the day. The brainchild of James Billmaier, Mario Pagliaro, Armando Stettner and Joseph DiNucci, the systems family was to also employ a truly RISC-based architecture when compared to the heavier and very CISC VAX or the then still under development PRISM architectures. At the time DEC was mostly known for their CISC systems including the successful PDP-11 and VAX lines.
Several architectures were considered from Intel, Motorola and others but the group quickly selected the MIPS line of microprocessors. The (early) MIPS microprocessors supported both big- and little-endian modes (configured during hardware reset). 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, and no version of the VMS operating system was ever released for DECstations. 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 (manage). 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.