The NXP MK20DX128VLL7 is a 32-bit ARM Cortex-M4 MCU from the Kinetis K20 series, clocked at 72 MHz with 128 KB Flash, 32 KB RAM, and 2 KB EEPROM on-chip.
Memory map and field-upgrade considerations
128 KB Flash holds a moderate firmware image — a bootloader plus one application slot, or two smaller slots if you partition for field-upgrade redundancy. 32 KB RAM supports a real-time OS with a few 1 KB task stacks and a 4 KB communication buffer. The 2 KB EEPROM is a genuine advantage: it stores calibration constants, fault logs, or configuration parameters without an external serial EEPROM, saving board space and one I²C or SPI bus. EEPROM endurance is typically 100k write cycles, so log-heavy applications should buffer writes in RAM.