A catalog in X games refers to a file containing number of another files.
A catalog is like an archive file - it contains set of another files. These are usually compressed to make the resulting catalog smaller.
The reasons why the files are put inside another file instead of being simply put in the game directory are:
- the resulting catalog is smaller than when all the files would be on real file system. That's because of cluster size.
- files in catalog might be accessesed more quickly then when they would be on real file system. This is not a rule but usually the catalog is stored at one place on hard drive which makes it quicker to Seek time|seek it. On the other hand when having hundreds of files, it is likely that they will be scatered all across the surface of the hard drive's platters, making the time to seek from one file to another much longer.
A catalog consists of two files: CAT file and DAT file. Those files have the same file name, but different extension:
- CAT files have extension .cat
- DAT files have extension .dat
CAT file contains names and sizes of files which are contained in the catalog. This file is cyphered. This is legacy from X: Beyond the Frontier and its sequels.
DAT file contains data of the contained files. Without the CAT file, there would not be any way to tell where data of certain file begin and end.
The original content of this article was imported from DeadlyDa and doubleshadow's X-Wiki.