What is Data Compression?
Data compression is a general term for a group of technologies that encode large files in order to shrink them down in size. The purpose is two-fold. Smaller files take up less room, leaving more storage real-estate. Also, smaller files are faster to transfer over a network, whether that network is the Internet, an intranet, or a local area network (LAN). In the 1970s various techniques were available to archive files, or place them together in a single package to avoid sending multiple files between computers. The idea was soon augmented with data compression techniques, thus an “archive” is now used to describe a compressed file. Data compression involves applying an algorithm to data that makes some of the repetitive bits unnecessary. You can think of it as a kind of shorthand map that gets stored with the compressed file. When decompressed, the map restores all of the missing bits, reconstituting the complete file. Data compression can be used with text, graphics, executable progra
The fastest straight serial data can be transmitted reliably over the phone lines is 600 bps. Data compression is a way of squeezing data into a tighter “space” so that its transmission can be sped up. This is done by grouping the data together and submitting several bits simultaneously in a more complicated sound. Compression is based on recursion algorithms (a fancy way of saying, “you done did that one; let’s move on”). Data compression can greatly improve the performance of a dial-up connection, but it is only possible when there is a protocol in place to handle lost data effectively, since every piece becomes so much more critical for the overall transmission. That is why you can only set a modem to compress data after you have turned error control on. And a modem will only compress data after error correction protocols have been established for a connection. MNP-5 and V.42bis are the standard protocols used for data compression today. MNP-5 has a compression rate of 2:1 and produ
