(RLL) The most popular scheme for encoding data on magnetic disks. RLL packs up to 50% more data on a disk than MFM.
IBM invented RLL encoding and used it in mainframe disk drives. During the late 1980s, PC hard disks began using RLL. Today, virtually every drive on the market uses some form of RLL.
Groups of bits are mapped to specific patterns of flux. The density of flux transitions is limited by the spatial resolution of the disk and frequency response of the head and electronics. However, transitions must be close enough to allow reliable clock recovery. RLL implementations vary according to the minimum and maximum allowed numbers of transition cells between transitions. For example, the most common variant today, RLL 1,7, can have a transition in every other cell and must have at least one transition every seven cells. The exact mapping from bits to transitions is essentially arbitrary.
Other schemes include GCR, FM, Modified Frequency Modulation (MFM). See also: PRML.
adjective, Baseball. 1. without having scored a run; without runs: a runless inning.
noun 1. a small stream; brook; rivulet. 2. a small channel, as for water. noun 1. (archaic) a cask for wine, beer, etc noun 1. (literary) a small stream
- Run like clockwork
see: like clockwork
verb (used without object), ran, run, running. 1. to go quickly by moving the legs more rapidly than at a walk and in such a manner that for an instant in each step all or both feet are off the ground. 2. to move with haste; act quickly: Run upstairs and get the iodine. 3. […]