https://www.arithmeum.uni-bonn.de/en/collection/calculating-in-olden-times/object.html?tx_arithinventory%5Bobject%5D=14415&L=2
Comptometer Educator
comptometereducator
https://www.arithmeum.uni-bonn.de/en/collection/calculating-in-olden-times/object.html?tx_arithinventory%5Bobject%5D=77&L=2
Comptometer JS
comptometerjs