  right|300px|thumb|vlsi layout of an inverter circuit using magic software magic is a very-large-scale integration layout tool originally written by john ousterhout and his graduate students at uc berkeley during the 1980s. as free and open-source software, subject to the requirements of the bsd license, magic continues to be popular because it is easy to use and easy to expand for specialized tasks. the current version is 7.5, but 6.x is still widely used. ==differences== the main difference between magic and other vlsi design tools is its use of "corner-stitched" geometry, in which all layout is represented as a stack of planes, and each plane consists entirely of "tiles" (rectangles). the tiles must cover the entire plane. each tile consists of an (x, y) coordinate of its lower left-hand corner, and links to four tiles: the right-most neighbor on the top, the top-most neighbor on the right, the bottom-most neighbor on the left, and the left-most neighbor on the bottom. with the addition of the type of material represented by the tile, the layout geometry in the plane is exactly specified. the corner-stitched geometry representation leads to the concept of layout as "paint" to be applied to, or erased from, a canvas. this is considerably different from other tools that use the concept of layout as "objects" to be placed and manipulated separately from one another. each concept has its own strengths and weaknesses in terms of both practical use and speed of computation. the corner-stitched representation is particularly well suited to searches within a single plane, for which it excels in speed. it is not particularly well suited to extremely large databases: the need to maintain four pointers for each tile, as well as the need to store tiles representing the space between areas of material on a layout, makes it more memory-intensive than object-based representations. an extension to the corner-stitched geometry representation called the "split tile" method, added in version 7.1, allows true representation of non-manhattan geometry. this method a
Electronic_design_automation_software_for_Linux Free_computer-aided_design_software Integrated_circuits