If you install system software or application software from an unlocked floppy disk or unlocked removable cartridge (often called a Syquest cartridge) which uses an Installer application onto a system infected with a virus, that unlocked disk can become infected.
From that point on, every system you use that Installer disk on becomes infected.
To prevent any viruses from spreading, you must know your master disks are clean, and you must use them only in a locked state. You can also use CD-ROMs, such as Apple's InstallMeFirst CD which are read-only disks and have been checked for viruses before production.
Article Change History:
1 April 1994 - Added information on other locked media, as well as CD-ROM's
25 August 1993 - Removed references to specific viruses and virus
software that was outdated information.
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