a) To lower the cost of of providing computing capability, time-sharing and multiprogramming made it possible for individuals and organizations to use ocmputer without owning one (such as in Internet Cafes, laborities in school, etc.). It also promotes the interactive sense of using computers.
Some computer laboratories in schools as an instance. Because users share the system simultaneously, they have the opportunity to copy other user's file from the system. Once a user saves a file to his/her unit, other users of that group or connected system may also have an access to the file. Other users may change an information inside the file or even steal the file from the owner itself without the owner knowing it. They may also modify the files or programs that was saved or ran by the owner. Furthermore, some of the threats that the owner of a certain file may encounter is the data confidentiality. Without him not being aware of the system used as the time-sharing and multiprogramming, he may insert or have a secret or confidential data that he wants to remain at the file. Another one is the data integrity. Other users may change, add, or even remove some information in the file if he wants to.
Internet cafes also have a multiprogramming and time-sharing environment. Some internet cafes have hardwares like printers that is also connected with the system. State that a certain user is asking the attendant to print a certain file form his unit. The file now is being printed. There comes this another user that accidentally hit the print button and clicked OK, so the file is being processed to be printed. The result is, it will interrupt the current printing process . It will cause the printer to mix output in printing the data because the other user is now accidentally printing his own file. Because they...