Abstract-The Teramac configurable hardware system can execute synchronous logic designs of up to one million gates at rates up to l megahertz. A fully configured Teramac includes half a gigabyte of RAM and hardware support for large multiported register files. The system has been built from custom FPGA's packaged in large multichip modules (MCMs). A large custom circuit (-1,000,000 gates) may be compiled onto the hardware in approximately 2 hours, without user intervention. The system is being used to explore the potential of custom computing machinery (CCM).