Operating systems

1. (6 pts.) A computer has both main memory and a hard disk. Suppose every instruction first requests a data word from memory. If the word is in memory, it can access it immediately. However, if the word is not in main memory, it must access the hard disk to obtain the word. If 70% of the words referenced are found in main memory (ie, do not require disk access), what is the AVERAGE access time for this computer system if: Main memory access time.005 ms Disk seek time Disk search time Disk transfer time .75 ms -.175 ms -,075 ms 2. (15 pts.) Consider a file sharing system in which there are five users (Userl, User2,...) and four files (File1, File2, ...). Each user is the owner of the file that has the same number as they do and they have read, write, execute, and delete access to that file. In addition: o Userl also has read and write access to File2, and execute access to File4 o User2 also has read and execute access to Filel, and read access to File4 o User3 also has read access to File1, and write and delete acess to File2 o User4 also has execute access to File3 o User5 has read and execute access to all files except File3. a. Show the Access Control Matrix for the above system. b. Show the Access Control Lists for the above system. c. Show the Capabilities List for the above system