VAX was an instruction set architecture (ISA), developed by Digital Equipment Corporation (DEC) in the mid-1970s. The VAX-11/780, introduced on October 25, 1977, was the first of a range of popular and influential computers implementing that architecture.
A 32-bit complex instruction set computer based on DEC's earlier PDP-11, VAX ("virtual address extension") was designed to extend or replace DEC's various PDP ISAs. The VAX architecture's primary features were virtual addressing (for example demand paged virtual memory) and its orthogonal instruction set.
VAX has been perceived as the quintessential CISC ISA, with its very large number of programmer-friendly addressing modes and machine instructions, highly orthogonal architecture, and instructions for complex operations such as queue insertion or deletion and polynomial evaluation.
The name "VAX" originated as an acronym for virtual address extension, both because the VAX was seen as a 32-bit extension of the older 16-bit PDP-11 and because it was (after Prime Computer) an early adopter of virtual memory to manage this larger address space. Early versions of the VAX processor implemented a "compatibility mode" that emulated many of the PDP-11's instructions, and were in fact called VAX-11 to highlight this compatibility and the fact that VAX-11 was an outgrowth of the PDP-11 family. Later versions offloaded the compatibility mode and some of the less used CISC instructions to emulation in the operating system software.
Vax UK Ltd is a brand that retails electrical goods and cleaning products in the floor-care sector, and which has its headquarters in the United Kingdom. The brand is owned, and its products are manufactured by, a company called TTI Co. Ltd Group, which is based in Hong Kong, China. Vax UK Ltd has its main headquarters in the city centre of Birmingham, West Midlands and a service, warehouse and depot operation in the village of Hampton Lovett, near Droitwich, Worcestershire.Vax branded machines are manufactured in China.
Vax UK Ltd was founded in December 1977 by Alan Brazier, who had prior experience in the field of industrial carpet cleaning. Brazier developed a prototype of a machine suitable for a household but capable of washing carpets and handling accident spillages or flooding. In 1979, Vax launched an "orange tub" multi-functional floor-care machine to fulfil this purpose and initially engaged with consumers by door-to-door sales of the device. This product was a world first.
VAX or Vax may refer to: