MIS is both an interactive and a batch-oriented multilevel logic synthesis and minimization system. MIS starts from the combinational logic extracted, typically, from a high-level description of a macrocell. It produces a multilevel set of optimized logic equations preserving the input-output behavior. The system includes both fast and slower (but more optimal) versions of algorithms for minimizing the area, and global timing optimization algorithms to meet system-level timing constraints. This paper provides an overview of the system and a description of the algorithms used. Included are some examples illustrating an input language used for specifying logic and don't-cares. Parts on an industrial chip have been re-synthesized using MIS with favorable results as compared to equivalent manual designs.

MIS: A Multiple-Level Logic Optimization System

Technology binding is the process of mapping a technology independent description of a circuit into a particular technology. This paper outlines a formalism of this problem and offers a solution to the problem in terms of matching patterns, describing technology specific cells and optimizations, against a technology independent circuit represented as a directed acyclic graph. This solution is implemented in DAGON. DAGON rests on a firm algorithmic foundation, and is able to guarantee locally optimal matches against a set of over three thousand patterns. DAGON is an integral part of a synthesis system that has been found to provide industrial quality solutions to real circuit design problems.

/pdf/dagon-technology-binding-and-local-optimization-by-dag-3nh3w23mp8.pdf

DAGON: Technology Binding and Local Optimization by DAG Matching

A survey of logic synthesis techniques for multilevel combinational logic is presented. The goal is to provide more in-depth background and perspective for people interested in pursuing or assessing some of the topics in this emerging field. Introductions, capsule summaries, and, in some cases, detailed analysis of the synthesis methods that have become established as practically significant are provided. Also included are some methods that have theoretical interest and potential for future impact. The discussion covers notation and definitions, representation of the network and nodes, logic decomposition/restructuring, logic optimization/minimization, logic synthesis and testing, and technology mapping. >

Multilevel logic synthesis

An approach is described for the minimization of multilevel logic circuits. A multilevel representation of a block of combinational logic is defined, called a Boolean network. A procedure is then proposed, called ESPRESSOMLD, to transform a given Boolean network into a prime, irredundant, and R-minimal form. This procedure rests on the extension of the notions of primality and irredundancy, previously used only for two-level logic minimization, to combinational multilevel logic circuits. The authors introduce the concept of R-minimality, which implies minimality with respect to cube reshaping, and demonstrate the crucial role played by this concept in multilevel minimization. Theorems are given that prove the correctness of the proposed procedure. Finally, it is shown that prime and irredundant multilevel logic circuits are 100% testable for input and output single-stuck faults, and that these tests are provided as a byproduct of the minimization. >

Multi-level logic minimization using implicit don't cares

Since the delay of a circuit is determined by the delay of its longest sensitizable paths (such paths are called critical paths), the problem of estimating the delay of a circuit is called critical path problem One important aspect of the critical path problem is to decide whether a path is sensitizable A framework which allows various previously proposed path sensitization criteria to be compared with each other in a unified way is presented An exact path sensitization criterion and a looser path sensitization criterion based on the framework are also proposed >

Path sensitization in critical path problem

For some time we have been exploring methods of transforming functional specifications into hardware implementations that are suitable for production. The complexity of this task and the potential value have continued to grow with the increasing complexity of processor design and the mounting pressure to shorten machine design times. This paper describes the evolution of the Logic Synthesis System from an experimental tool to a production system for the synthesis of masterslice chip implementations.

The system was used by one project in IBM Poughkeepsie to produce 90 percent of its more than one hundred chip parts. The primary reasons for this success are the use of local transformations to simplify logic representations at several levels of abstraction, and a highly cooperative effort between logic designers and synthesis system designers to understand the logic design process practiced in Poughkeepsie and to incorporate this knowledge into the synthesis system.

Jonh V. Gerbi

Papers

LSS: a system for production logic synthesis