Sharing can lead to problems Process p1 Process P2 input (in, keyboard) input(in, keyboard) out:=in out: =in output (out, display output (out, display) So, it is necessary to protect shared global variables PROCESSES AND SCHEDULINGPROCESSES AND SCHEDULING Sharing can lead to problems Process P1 . input (in, keyboard) . out:=in output (out, display) . . Process P2 . input (in, keyboard) . out:=in output (out, display) . . So, it is necessary to protect shared global variables