Inside Java Card: JVM for Battery-Less Microcontrollers

Java Card powers billions of SIM and bank cards using a highly stripped-down JVM designed for battery-less microcontrollers. By flipping traditional memory management on its head, it stores the object heap in non-volatile flash memory rather than volatile RAM, ensuring data survival when power is instantly cut mid-transaction. I've always been fascinated by how extreme constraints breed the most elegant engineering. Take standard Java: it is a language most of us associate with heavy enterprise