Nintendo's website doesn't say, but the original games were released for the ZX Spectrum and Commodore 64.

https://spectrumcomputing.co.uk/entry/0005617

Unrelatedly, a "Monty Mole" is apparently a type of enemy in the Mario pantheon: https://www.mariowiki.com/Monty_Mole

It's crazy, but amazing, that this exists.