Whether using a PC or a Mac, for business or pleasure, valuable data should be protected from impending harm caused by a virus, hackers, power surges, human error, natural disasters and more. The most important step in keeping data safe from being deleted, stolen, lost or damaged is to back-up regularly. By doing so, if something should happen to threaten the integrity of the electronic information, users will still have a recent copy of all important files, emails, databases, spreadsheets and more.
A file system is a structure that organizes large numbers of files on some sort of recording medium (most commonly a disk drive). The idea is to store the files on the disk so that they can be accessed randomly and with minimal time delay. The PC and Mac differ in the way they store files. These differences can make it difficult when copying files between platforms. Not all Mac files will be useful on a PC and vice versa. Executable program files compiled for one platform cannot be used on the other, but there are many that have a separate version for each platform.
On a Mac each file can have two parts called forks – a data fork and a resource fork. These are actually two files linked to one name in the Mac file system. The resource fork holds resources (icons, fonts, menus, sounds, etc.). Since each resource fork can hold many resources, it has a specific structure that allows programs to find and access a particular resource quickly. The data fork can hold any type of data (text, images, etc.) and does not have a required a structure like the resource fork. Mac resource forks are generally of no use on the PC, but it is possible for a PC program to convert specific resources to a PC format. Our program CrossFont can do this with Mac fonts which exist in the resource fork. The contents of the Mac data fork is usually all that can be used on a PC. Once a Mac file is copied to the PC, the resource fork, type and creator information are lost unless the file is encoded with MacBinary or a similar format (HQX, SIT, etc.) that saves the Mac specific data with the file. This way the file can exist on a single fork machine (PC, UNIX) or be telecommunicated and decoded at the other end with all Mac information intact.
It is useful to have a way to identify the type of a file as well as which application created it. The Mac file system has this information stored with the file name and other information. They are two four character fields called the type and creator. Mac programs can use many different types of files. The type field tells the program what type of data is in each file so it can parse it properly. It also allows a program to filter files in an open file dialog box so the user can only open files of a certain type. The creator field is unique for each Mac application. When an application creates a file, it puts a creator signature in this field which identifies that this application should be launched when a user double clicks on the icon of the file.