The AVR Central Processin Unit (CPU) is driven by the CPU clock clkCPU, directly generated from the selected clock source for the chip. No internal clock division is used. Parallel instruction fetches and instruction executions are enabled by the Harvard architecture and the fast-access register file concept. This is the basic pipelining concept to obtain up to 1 MIPS per MHz with the corresponding unique results for functions per cost, functions per clocks, and functions per power-unit.
The Parallel Instruction Fetches and Instruction Executions
In a single clock cycle an ALU operation using two register operands is executed, and the result is stored back to the destination