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Logic "mapping," or "transformation," refers to the process of converting a logic design from one form of specification to another. The output is usually a specific technology implementation and the input could range from a previous technology implementation to a high-level design language. Motivated initially by the problem of test case generation for new technologies, a logic transformation system, known as the Technology Mapping System (TMS), was developed. This system has focused on the problem of technology-to-technology mapping involving gate array or standard cell logic families. TMS makes use of an intermediate notation, called GLN, and uses several forms of "rules" to control the mapping process. This paper discusses the history and general operation of TMS, and makes a comparison of transformations from different types of sources. The terms mapping, remapping, transformation, and 1. High-level hardware design languages. 2. Array or truth table specifications such as Programmable 3. Technology-independent structures. 4. Technology-dependent structures such as the technologyspecific Basic Design Language for Structure (BDL/S) used by the IBM Engineering Design System (EDS). Logic Arrays (PLAs). The term synthesis is usually used with type 1, while remapping is often applied to type 4. There have been many efforts at logic transformation reported in the literature [ 11. One of the earliest efforts within IBM was the ALERT system in the late 1960s [2, 31. This system showed that a logic design could be automatically generated from a design language, but the results were not competitive with manual designs. More recently, the Logic Synthesis System (LSS) was developed [4-61. This system has brought design language synthesis of random logic from a promising idea to a practical reality. LSS has also been used for the remapping application.