The preferred design strategy for embedded CPU cores is reduced instruction set computer (RISC). Among all the RISC CPU architectures, a number of reference designs are used as guidelines by silicon manufacturers to produce the core logic to integrate into the microcontroller. Each reference design differs from the others in a number of characteristics of the CPU implementation. Each reference design includes one or more families of microprocessors integrated in embedded systems, sharing the following characteristics:
- Word size used for registers and addresses (8-bit, 16-bit, 32-bit, or 64-bit)
- Instruction set
- Register configurations
- Endianness
- Extended CPU features (interrupt controller, FPU, MMU)
- Caching strategies ...
