Project Madhat circuit boards will conform to the Eurocard standard for 9U boards which are 366.7 mm (14.437") high and 340 mm (11.386") deep.

Boards will connect to a backplane using three DIN-41612 96-pin male connectors. The connectors are designated as P1 (top), P2 (middle), and P3 (bottom).

P1 signals will conform to the NuBus standard (IEEE-1196) or be unused. If the board does not need access to the NuBus, it should still comply with NuBus power, ground, and slot identifier connections.

P2 and P3 will be used for the synchronous backplane interface (SBI) for boards that need to access the SBI. Boards that do not need access to the SBI can use P2 and P3 for board-specific I/O.

The backplane will provide three DIN-41612 96-pin female connectors for each board slot. The backplane will be split into a contiguous group of SBI slots and a contiguous group of non-SBI slots. All slots will provide NuBus on P1.

The P2 and P3 connectors for SBI slots will be bussed together. Non-SBI slots will have power and ground connections with all remaining pins on P2 and P3 unassigned and available for board--specific I/O.