> How does USB A deliver power differently such that it works with devices which don’t support USB PD? USB A devices (and by extension, USB A to USB C cables)

> How does USB A deliver power differently such that it works with devices which don’t support USB PD? USB A devices (and by extension, USB A to USB C cables) always delivers power. USB C devices only deliver power once they see a specific resistor to ground on a control pin. If the device is missing that resistor (actually a pair of resistors, one for each side of the cable), a USB C device on the end of a USB C to USB C cable won't provide power. (Preemptive nitpicking: actually, USB C devices provide a bit of power in that control pin, which is how they detect that resistor to ground; but that's separate from the main power pins.)