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1.                 From The Free On-line Dictionary of Computing (19 January 2023):
                   
   
   
                   
                     
   MB
      <unit> (Or "Mb") megabytes or megabits.  When referring to
      the size or data transfer rate of a storage device which is
      accessed in multiples of eight bits (e.g. RAM, hard disk)
      this almost certainly means megabytes, but when referring to
      the data transfer rate of a communications system it probably
      means megabits.  Some years ago, it is claimed, "MB" always
      meant megabytes and "Mb" meant megabits but recently this
      useful distinction has been lost.
      (1996-09-22)