The operating system is the computer’s control program. It allows users and their application to share and access common computer resources, such as processors, main memory, databases, and printers. If operating system integrity is compromised, controls within individual accounting applications may also be circumvented or neutralized. Because the operating system is common to all user, the larger the computer facility, the greater the scale of potential damage. Thus, with an ever-expanding user community sharing more and more computer resources, operating system security because an important internal control issue.