Alex had a problem. On his workbench sat a brand-new Windows 10 64-bit PC, and next to it, an old but faithful friend: the programmer. For years, this little grey box had flashed code onto countless ATmega and ATtiny microcontrollers. But today, it refused to speak to the new computer.

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Frustrated, Alex nearly gave up and ordered a newer programmer. But then, a memory surfaced: Atmel (now Microchip) never officially released signed 64-bit drivers for the original AVRISP mkII. Windows 10’s driver signature enforcement was blocking the old, unsigned driver. Instead of hunting for a magic download, Alex remembered a better way — use the driver that comes with modern Atmel Studio / Microchip Studio .