Atmega 8 bit avr microcontrollers atmel atmega644p 20pu the atmega644p 20pu 8 bit microcontroller 4k dil 40 is from a range of high performance microcontrollers featuring a wide range of peripherals megaavr offers substantial program and data memory and performance approaching 1 mips per mhz shares the same avr instruction set and memory organisation as attiny allowing for easy migration atmel atmega644p 20pu 8 bit microcontroller 4k dil40