Mixed-mode simulation tools for custom VLSI designs.

A system for performing concurrent VLSI simulation on a distributed processing system is presented. The system provides an expandable medium which allows the coexistence of existing different-level simulation programs. Several design examples including various word-length Manchester carry-chain adders, Booth-encoded multipliers, and one stage of a two-dimensional fast Fourier transform circuit have been simulated using RNL at the switch level, FACTS at the electrical level, and Lisp routines at the functional level. The largest circuit simulated thus far contains 29,000 transistors and was simulated in 24 concurrent processes executing on four SUN III workstations. The system can be further enriched by integrating other existing behavior, register-transfer, and logic-level simulation programs. The possibility of integrating an analog-circuit simulation program is currently being investigated.