Apple Computer Inc has released the System 7.5.5 Update of its Macintosh System and Mac OS operating systems. Under the new regime announced by Gilbert Amelio last month, Copland will be trickled out in pieces, and in January Apple will begin releasing the first phase of its new operating system. The second phase of Copland is due in mid-1997. Apple says System 7.5.5 Update eliminates some causes of system freezes and improves the reliability of sharing a printer over the network. It will install only on computers currently running System 7.5.3, including System 7.5.3 Revision 2. A free copy of System 7.5.5 Update can be downloaded from Apple’s File Transfer Protocol sites on the Internet at ftp.info.apple.-com/ or ftp support.apple.com/ , and its Web sites at http://www.info.apple com/ or http://www.support.apple.com/.