History of OS

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Across
  1. 3. 1971 - First OS in C Language
  2. 6. 1981 - Microsoft’s Disk OS
  3. 7. 2007 - Mobile OS by Apple Inc
  4. 8. 1992 - OS by Oracle
Down
  1. 1. 1991 - Open-source OS
  2. 2. 1985 - Computer OS by Microsoft
  3. 4. 1998 - First modern Mobile OS
  4. 5. Mobile OS by Google