Which of the statements below are true? Which are false? a. In polling, I/O devices set flags that must be periodically checked by the CPU.
b. When using interrupts, the CPU interrupts I/O devices when an I/O event happens.
c. The overhead of polling depends on the polling frequency.
d. Polling is often a viable option for slow and asynchronous devices.
e. Synchronous I/O cannot be done with interrupts.
f. User processes are always blocked during asynchronous I/O operations.
g. Traps are software-generated interrupts.
h. System-calls can be implemented using either traps or polling.
i. DMA usually improves the overall system performance.
j. DMA is necessary for asynchronous I/O transfers

Write a modular program (no classes yet, just from what you learned last year), that allows two players to play a game of tic-tac-toe. use a two-dimensional char array with 3 rows and 3 columns as the game board. each element of the array should be initialized with an asterisk (*). the program should display the initial board configuration and then start a loop that does the following: allow player 1 to select a location on the board for an x by entering a row and column number. then redisplay the board with an x replacing the * in the chosen location. if there is no winner yet and the board is not yet full, allow player 2 to select a location on the board for an o by entering a row and column number. then redisplay the board with an o replacing the * in the chosen location. the loop should continue until a player has won or a tie has occurred, then display a message indicating who won, or reporting that a tie occurred. player 1 wins when there are three xs in a row, a column, or a diagonal on the game board. player 2 wins when there are three ox in a row, a column, or a diagonal on the game board. a tie occurs when all of the locations on the board are full, but there is no winner. input validation: only allow legal moves to be entered. the row must be 1, 2, or 3. the column must be 1, 2 3. the (row, column) position entered must currently be empty (i.e., still have an asterisk in it).