Anyone who has seen the movie Honey I shrunk the kids' can imagine how useful compression can be. Compression, which has become anonymous with Zip files work off the same idea only with a (add your joke here)'slightly' different technology. You will find a lot of data compression programs in use today and some are easier and have better features than others, so in this article I will talk about compression in general, but may through in a couple of examples for comparison. The first thing you need to know is that there can be more than one compressed file; you can have an archive (a multiple of files). The main benefit of this is that the user can: *Save valuable disk space *Can send and receive files on the internet quicker *Speeds up your processor *Depending on the file compression program can reduce files as much as 90% The user should also be aware that files can only be opened with the original compression program that compressed it. Think of this as a form of protection, if you will since this is like an encrypted file or archive. Adding a password is another way to insure files are safe from prying eyes and some compression programs let you do this at any level of compression or decompression with the associated commands (update,move,feshien,add). Only individual files can be password protected not whole archives. Ever since the first personal computers (PC's) came about people found how easy it is to load up there drives with programs and downloads that eat up much of there memory. That's why developers created data compression programs in the first place, to free up hard drive space and increase processor speed. There are a lot of data compression programs and they are not exactly alike because they use different data compression algorithms. One popular program, for example looks for repeating words or phrases and assigns them there own character or number value. A lot of users don't fully understand the more advanced features of their data compression programs so they are not really getting there full value. Syntax command lines are a good example of this confusion. There are four basic commands in syntax (the shape of a command line); *Command: The task to be preformed like add, delete or update. *Archive: the name of the archive. *Switch or Option: lets user specify a file option like adding file directories for compression. *File: name of file(s) to be processed. A user can compress files four basic ways: *Add files to archive - old files with same name are overwritten. *Move files to archive - upon compression old files are deleted. *Update files - makes sure you have the most recent file version. *Freshen files - almost like update, seeks out the last modified file and adds it to archive. The above commands have there basic functions but can do other things. Ex. the update & add commands can create and compress files and the Freshen command can create a new archive. There are only a couple of data compression programs out there that give the user more than one compression method - PKZIP AND ARJ. PKZIP has what they call an imploding method and a shrinking method; without going into great detail imploding uses less memory (90k), and is very through. This is the default setting. Shrinking is fast but uses a bit more memory (128k), works great for smaller files. ARJ gives the user more options for data compression. It uses multiple settings (m1 to m4), This is a tradeoff of prosessing speed versus packing dentisy. There are 2 more options available here but test runs show no significant change in time or compression. Even with experienced compression users, extracting compressed files with a newer version of a data compression program may prove difficult, so programmers created self extracting files (SFX) to enable beginners to easily use compressed files. This small program may be part of the original program or added after as a separate program. I realize some of this may sound confusing and for that I apologize, and after all, people will compresses data using only the basic functions and be happy and content because it suits there present needs. In conclusion you can tell there are many options available when using any data compression program and it is well worth the time (got time on the week end?) and effort to learn some of the advanced features if you want to save some serious space on your hard drive. |
