The WD16 is a 16-bit microprocessor introduced by Western Digital in October 1976. It is based on the MCP-1600 chipset, which formed the basis of the DEC LSI-11 low-end minicomputer and the Pascal MicroEngine processor designed specifically to run the UCSD p-System efficiently. Each used different microcode. The WD16 implements an extension of the PDP-11 instruction set architecture but is not machine code compatible with the PDP-11. The instruction set and microcoding were created by Dick Wilcox and Rich Notari. The WD16 is an example of orthogonal CISC architecture. Most two-operand instructions can operate memory-to-memory with any addressing mode and some instructions can result in up to ten memory accesses.