Penny's OS (S 9)

   
or IAS or IBM AOS
or IBM DOS or IBM 1410/1710
or IBM i or IBM PC-DOS
or IBM 360/30 or IBM Workplace OS
or IBOX or IBSYS
or Icaros Desktop or ICE-Linux
or Icepack Linux or ICL/Unix
or ICL VME or IDA
or IDMS Linux or IDRIS
or i5/OS or Igelle
or Ignalum or IJMON
or ILIOS or iloog
or iMAX or IMDOS
or Immunix or IMOS
or Impi Linux or Independence
or Indlinux or Inferno
or INMOS or INOS
or Input Output Selector or Input Output System
or INTEGRITY or INTEGRITY-178B
or Interactive IS or Interactive UNIX
or IOCS or ioRTOS
or iOS or IOS XR
or IPCop or iPhone OS
or iPodLinux or ipolyBSD
or Iridium OS or IRIS GL2
or IRIX or iRMX
or IRTS or IRX
or ISA or ISC
or ISIS or ISIS-II
or IS/1 or ISOS
or ISSL or IS/3
or Italios or ITRON
or ITS