Penny's OS (S 20)

 
or Tablix or Tabos
or TAJ or TajOS
or Talon DSP RTOS or TalOS
or Tao or TAOS
or Tape Scope 2 or Taprobane GNU/Linux
or Taste or TDOS
or TechLinux or TENEX
or T.H.E. or THEOS
or ThinBSD or Thinstation
or Thix or Thoth
or ThreadX or 3Anoppix
or 3BSD OR 386BSD
or 386/ix or ThrillOS
or Tigger or Tilix
or Timos or Tinfoil Hat Linux
or Tin Hat Linux or TinOS
or TinyMe or TinyOS
or TI System V or TITAN
or TJI-OS or Tmax Window
or TME or TMX
or TNIX or TNKernel
or tomsrtbt or Tomukas
or Toophpix or TopDOS
or Topix or Topologilinux
or TOPS-10 or TOPS-20
or Topsy or Tornado
or Torsion or TOS
or TOS/360 or Toutou
or Towns OS or TPF
or TP/M or Trampoline
or tresos or Triance OS
or TriangleOS or Trinity
or Trio or Trion
or TripOS or Trisquel
or TRIX or TrixBox
or TRK or TRON
or Tropix or Troppix
or TRS-DOS or TrueBSD
or Tru64 UNIX or Trusted IRIX
or Trusted Solaris or Trusted Xenix
or Trustix or Truva
or TS or TSB
or TS8/E or TSM
or TSOS or TSS
or TSS-8 or TSS/360
or TSX or TSX-PLUS
or TSX-32 or TUD:OS
or TumiX or TUNES
or TUNIS or TupiServer
or Tuquito or TurboDOS
or Turbolinux or Turkix
or TurnKey Linux or 2200T
or 2200VP or 2200VS
or 2K or TWOS
or 2000E or 2000F