In this paper we present methods for generating bounds on interconnection delays in a combinational network having specified timing requirements at its input and output terminals. An automatic placement program which uses wirability as its primary objective could use these delay bounds to generate length or capacitance bounds for interconnection nets as secondary objectives. Thus, unlike previous timing-driven placement algorithms described in the literature, the desired performance of the

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... it is guaranteed when a wirable placement meeting these objectives is found. We also provide fast algorithms which maximize the delay range, and hence the margin for error in layout, for various types of timing constraints. * * Ravi Nair (M'82-SM'87) received the B . Tech. degree in electronics and electrical communications engineering from the Indian Institute of Technology, Kharagpur, India, in 1974. He received the M.S. and Ph.D. degrees in computer science from the University of Illinois, Urbana, in 1976 and 1978, respectively. Since 1978, he has been with IBM at the Thomas J . Watson Research Center, in Yorktown Heights, NY. During 1987-1988 he was on sabbatical leave at Princeton University in the Department of Computer Science. He has worked on computer synthesis and analysis of VLSI layout, parallel machines for physical design, fault-tolerant systems, and testing. He is interested in algorithms and systems for the design of digital integrated circuits. * Ellen J. Yoffa (M'86) received the B.S. and Ph.D. degrees in physics from the Massachusetts Institute of Technology, where her area of study was theoretical solid-state physics. In 1978, she joined the IBM Thomas J . Watson Research Center for postdoctoral work in the Semiconductor Science and Technology Depanment, where she investigated ballistic conduction in semiconductor devices and the physics of the laser annealing process. Since 1980, she has been a member of the research staff in the Computer Science Department and is currently senior manager of the System Design and Verification Department, where she is responsible for managing research in tools for computer-aided design of VLSI chips, including system description and early design tools, logic synthesis, and hardware and software logic simulation. She is a member of the editorial board of lEEE Design and Tesf of Computers. Her research has involved the development of tools for VLSI physical design automation. Dr. Yoffa is a member of Phi Beta Kappa and Sigma Xi.