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Across
  1. 3. the operation of a computer system by several users for different operations at the same time
Down
  1. 1. a program that resides in the computer's EPROM, ROM, or other non-volatile memory.
  2. 2. an open-source operating system used for smartphones and tablet computers.
  3. 4. sharing system software that manages computer hardware and software resources and provides common services for computer programs.