While the HP 3000s were initially mini-mainframes, the final high-end systems supported 12 CPUs and over 2000 simultaneous users.
It runs on the HP 3000 family of computers, which originally used HP custom 16-bit stack architecture CISC CPUs and were later migrated to PA-RISC where the operating system was called MPE XL.
MPE XL was written primarily in Pascal, with some assembly language and some of the old SPL code.
In 1992, the OS name was changed to MPE/iX to indicate Unix interoperability with the addition of POSIX compatibility.
The discontinuance of the product line was announced in late 2001, with support from HP terminating at the end of 2010.