Design and implement a Demand Paging virtual memory simulator! It must be a text based application (NOT a GUI based one). You can use the C/C++ or Java programming language. The following algorithms must be implemented: FIFO, OPT, LRU and LFU. The application must simulate the execution of each of these algorithms on a hypothetical computer having only N physical frames (numbered from 0 to N-1, N<8), assuming that the single process that is running has a virtual memory of ten frames (numbered from 0 to 9). The number N should be a number provided in the command line as an argument. The algorithms will be simulated based on a reference string (a sequence of pages that are to be accessed) that will be either read from the keyboard or randomly generated. THE SIMULATION MUST FOLLOW THE ANIMATED EXAMPLES FROM THE ONLINE MODULE 3 AS CLOSE AS POSSIBLE IN ALL ASPECTS !!! The program should be menu-based and the menu will keep the user in a loop containing the following options: 0 - Exit Will exit the program

1 - Read reference string A reference string will be read from the keyboard and stored in a buffer. Each value of the reference string will be verified and validated (or rejected). Using option 1 again will result in overwriting the old reference string.

2 - Generate reference string A reference string will be randomly generated; the length of the reference string will be given by the user interactively. The string will be stored in a buffer. Using option 2 more than once will result in overwriting the old reference string.

3 - Display current reference string Will display the stored reference string; if there is no reference string stored yet, an error message will be displayed.

4 - Simulate FIFO Will simulate the step by step execution of the FIFO algorithm using the stored reference string; if there is no reference string stored yet, an error message must be displayed. The user will press a key after each step of the simulation to continue the simulation. The total number of faults will be displayed at the end of the simulation.

5 - Simulate OPT Will simulate the step by step execution of the OPT algorithm using the stored reference string; if there is no reference string stored yet, an error message must be displayed. The user will press a key after each step of the simulation to continue the simulation. The total number of faults will be displayed at the end of the simulation. 6 - Simulate LRU Will simulate the step by step execution of the LRU algorithm using the stored reference string; if there is no reference string stored yet, an error message must be displayed. The user will press a key after each step of the simulation to continue the simulation. The total number of faults will be displayed at the end of the simulation.

7 - Simulate LFU Will simulate the step by step execution of the LFU algorithm using the stored reference string; if there is no reference string stored yet, an error message must be displayed. The user will press a key after each step of the simulation to continue the simulation. The total number of faults will be displayed at the end of the simulation. Selecting a different option will result in an error message but the user will NOT exit the loop!