(Virtual Address eXtension) A venerable family of 32-bit computers from HP (via Digital and Compaq) introduced in 1977 with the VAX-11/780. VAX models ranged from desktop units to mainframes all running the same VMS operating system, and VAXes could emulate PDP models (Digital's first computers). Large VAX multiprocessing clusters served thousands of users.A Very Successful Computer LineThroughout the 1980s, software compatibility among all models caused the VAX family to achieve outstanding success for Digital. The last VAX order was taken in 1999 (for VAXstation 4000s), 22 years after the first VAX. HP supported OpenVMS on VAX through 2010 while offering migration to its 64-bit Alpha platform.