Windows embedded/CE was (and still is to some extent) very popular for embedded systems with a GUI, such as ATMs, POS systems, PLCs, graphical medical devices,

Windows embedded/CE was (and still is to some extent) very popular for embedded systems with a GUI, such as ATMs, POS systems, PLCs, graphical medical devices, etc. Microsoft even sold an SKU called Windows Embedded POS/POSReady For headless non-GUI systems windows is/was much less of a contender, RTOS is more likely