b) Windows Linux windows comercial Linex open sure b) Give 2 different operating systems that can be used in a personal computer. Which of them are open-source and which of them are commercial? [4 marks] Q2. (a) List the functions of these parts of the CPU: (i) Program counter (ii) Stack pointer (iii) Program status word (PSW) 29) i) keep track of memay location of next Instruction (ii) point the stack when graving towards the Heap li registers that perform the function of status Q6 a) Actual passwords are stored in leta shadow and not lets/passwd. Der etc passwd hold information about VID, GID that is important to be read by alli Vsers. Q6 (a) root:x:0:0:root:/root:/bin/bash bin:x:1:1:bin:/bin:/sbin/nologin daemon:x:2:2:daemon:/sbin:/sbin/nologin adm:x:3:4:adm:/var/adm:/sbin/nologin nobody:x:99:99: Nobody:/:/sbin/nologin user:x:500:500:RHEL5:/home/user:/bin/bash Examine the listing above extracted from the /etc/passwd file. i) Why must the /etc/passwd be set to readable by all users? What is the shell that is used by user? Are users adm and nobody allowed to log into the system? Why? What is the UID and GID of the root? [4 marks]