An MPU is a digital IC that includes an instruction decoder, ALU, registers and additional logic. It may contain instruction, data or unified caches, memory management systems, and auxiliary ALUs for floating point, vector, media and other special data types. An MPU's function is determined by retrieving and executing a sequence of instructions that manipulate data held in registers, cache, memory or I/O peripherals. More highly integrated MPUs may contain sophisticated on-chip peripherals, bus and memory interfaces, and support circuits. Processors that are a core of an ASIC or ASSP are not included in this general-purpose category.
Digital Signal Processor (DSP)
A DSP constitutes a high-speed arithmetic unit, typically including a multiplier-accumulator nit (MAC) designed to perform complex mathematical operations, such as Fourier transforms in real time to generate, manipulate or interpret digital representations of analog signals. DSP's are typically used to process real-time data. As an example, the retrieval and execution of instructions and manipulating data held in registers, internal memory or external memory determine a DSP's operation. Modem DSPs typically access multiple data in different locations of on-chip memory over separate data paths using specialized addressing modes. Most DSP operations, such as the MAC, complete in a single clock cycle. DSPs usually include peripherals, which may include analog circuits, such as analog-to-digital converters.