The Osprey is a standard EISA/ISA PC card. Figure 1 displays a diagram of the board. It has a DCJ11 microprocessor (manufactured by Digital Equipment Corporation), memory, and a Xilinx programmable gate array. The DCJ11 executes Digital's PDP-11/94-94 instruction set at either 15 MHz or 18 MHz. The Osprey/15(B, Q, U) uses the 15MHz DCJ11-AC. The Osprey/18(B, Q, U) has a DCJ11-AE microprocessor running at 18 MHz.
We've given the Osprey 4 Mbytes of tightly-coupled memory with zero wait states (just like the 11/93-94). That's one reason it runs as least as fast as the 11/93.
The Xilinx chip, initialized at start-up, provides "glue" logic.
The x86 microprocessor, with its associated SRAM (Static Random Access Memory), acts as the Virtual I/O CPU.