The IBM ASIC design methodology enables a product developer to fully incorporate the high-density, high-performance capabilities of the IBM CMOS technologies in the design of leading-edge products. The methodology allows the full exploitation of technology density, performance, and high testability in an ASIC design environment. The IBM ASIC design methodology builds upon years of experience within IBM in developing design flows that optimize performance, testability, chip density, and time to market for internal products. It has also been achieved by using industry-standard design tools and system design approaches, allowing IBM ASIC products to be marketed externally as well as to IBM internal product developers. This paper describes the IBM ASIC design methodology, and then focuses on the key areas of the methodology that enable a customer to exploit the technology in terms of performance, density, and testability, all in a fast-time-to-market ASIC paradigm. Also emphasized are aspects of the methodo logy that allow IBM to market its design experience and intellectual property.