Penny's OS 2.0 (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