They're kind of dedicated. Some have their own IRQ, but some of them share an IRQ. All 16 can be active.
You'd have to check the datasheet for exact details, but they shouldn't matter.
@Gordon started
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
They're kind of dedicated. Some have their own IRQ, but some of them share an IRQ. All 16 can be active.
You'd have to check the datasheet for exact details, but they shouldn't matter.