A. Processor Architecture and Instruction Set
Most general-purpose microprocessors and microcontrollers use the Von Neumann architecture in which data and instructions are stored in the same memory and travel over the same bus set. One major limitation of this architecture is that pipelined operation of instructions and data transfer is not possible. The processing speed is thus limited by the bus bandwidth.
The instruction sets of general-purpose microprocessors and microcontrollers can handle both basic operations and complex functions. Typically, the instructions are microcoded and can take many clock cycles to complete. Because of the complexity of their instruction sets, these processors are designated as complex-instruction-set computing (CISC) processors.