My AHX music Ripping Exotic Team Turrican 2 maps One of the interesting things in computers is data compression. However, this is not a full discussion of the history and theories involved in it, rather how it was applied by Amiga programmers. The purpose of this page is to tell you about XFD and XAD libraries, and the slaves and clients I have written for these libraries. If you want to know about other slaves and clients available for these libraries, you should check the documentation included with their distributions. For a long time, since the days of the C64, game and demo programmers have used compression, known as 'crunching', with realtime decompressors, aka 'decrunchers', internally their software, so they can fit more on their disks.
Raster graphics take a lot of space and can be compressed very well.
Also, it's quite fashionable to write small demos called 'intros'. These often compete at parties, and have a size limitation - 64kb, 40kb or 4kb. With an executable file compressor, it is possible to fit around 200kb of data in a 64k file, and as much blank space as you want. Technically, most Amiga compression formats are based on a mix of delta precoding, run length encoding, Lempel-Ziv style dictionary compression and Huffman style entropy compression. That's because these are the easiest and most well known methods in existance.