The most serious drawback of distributed networks is the difficulty in maintaining adequate control and security. Each of the distributed processing locations requires its own set of controls and security measures. Because each location is relatively small, organizational independence is not easily achieved. Also, certain managers are likely to sacrifice control and security for greater productivity. A related drawback is the difficulty of coordinating the relatively independent and sometimes incompatible computing systems. That is, computers made by one manufacturer and using a particular operating system will often not transfer data to hardware made by another manufacturer. An operating system such as Unix will not easily "talk" to the Windows 98 or NT operating system. A third drawback is added costs for the multiple computers, other system components, and communications services, as well as the cost of attempting to blend dissimilar computer systems. Figure 3-2 contrasts the advantages of centralized and distributed networks.