(Patlabor: The Movie)
Hyper Operating System, the embedded realtime operating system found in most Labor mechas. Developed by Shinohara Heavy Industries.
Unlike most MovieOS grade operating systems, you can actually see the boot messages¹ scroll by on head display - in English - and after that the thing behaves just as unnoticeably as your average embedded system... (see AnimeOS.)
The movie opens with the suicide of the head designer of the HOS, and continues with couple of rather strange and dangerous glitches... and the mobile police tries to find out this, and ends up discovering the greatest and the most devilish time bomb ever seen in virus circles that has been added to the new HOS release...
¹ If I ever get this movie on DVD, I'll include the messages here =)