hewlett packard multi processing executive

from The Free On-line Dictionary of Computing (8 July 2008)

Hewlett Packard Multi Processing Executive
HP-MPE

   <operating system> (HP-MPE) The standard {operating system} on
   all {HP3000} {minicomputers}, in the same way that HP9000
   computers run {HP-UX}.

   Latest version: MPE/IX Version 5.5.04, as of 1998-02-17.

   (1998-02-17)