Experience with CAD Tools for a 32-Bit VLSI Microprocessor

As the complexity of VLSI devices increases, so does the need to rely on computer aided design (CAD) methods. As VLSI designs grow they push the limits of the CAD tools, and in some cases require new approaches to design and verification. This paper reports on experiences with a particular approach taken to design a 170,000 transistor single chip CMOS microprocessor. The chip was an implementation of the Bell Labs C-Machine 1, 2 architecture, code-named CRISP (C-Machine Reduced Instruction Set Processor) during its design. The major design tools used are described along with pleasant and unpleasant surprises in their use. Problems with more traditional approaches due to the increased size of designs are discussed.