ARC is used to create and maintain file archives. An archive is a group of files collected together into one file in such a way that the individual files may be recovered intact. ARC automatically compresses the files being archived so that the resulting archive takes up a minimum amount of space.
When ARC is used to add a file to an archive it analyzes the file to determine which of three storage methods will result in the greatest savings. Since one of the three methods involves no compression at all, the resulting archive entry will never be larger than the original file.
ARC provides a full range of functions for archive creation and maintenance. ARC also provides password encryption to protect your data from unauthorized use.
While the exact degree of compression achieved will vary depending on the contents of any given file, typical compression rates are as follows:
Programs (.EXE and .COM) files - 20% to 30%
ASCII text and documents - 50% to 60%
Spreadsheets - 50% to 90%
ARC calculates a cyclical redundancy check (CRC) on every file it puts in an archive and recalculates it whenever a file is extracted. This helps to ensure data integrity when archives are transmitted over telephone lines.