 Motorola MC68HC805 was the first microcontroller to use EEPROM to store the firmware.EEPROM microcontrollers became more popular in 1993 when Microchip introduced PIC16C84 and Atmel introduced an 8051-core microcontroller that was first one to use NOR Flash memory to store the firmware.Today's microcontrollers almost exclusively use flash memory, with a few models using FRAM, and some ultra-low-cost parts still use OTP or Mask-ROM.