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.
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.
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 and VAX lines.