This group has been in operation for about 20 years, initially in Yahoo, it migrated to groups.io after the closure of Yahoo groups in 2019. As an autodidact my recognition to its members is immense since without their contributions, synthesized on Totton Heffelfinger's website, I couldn't have gone on. So I like to say that this group is my Alma Mater when it comes to the abacus.
This page is still in a very primitive state...
Soroban Trainer, follow the instructions on the page.
Some articles by Hisao Suzuki (Japanese)
Abaci (Simulators of many types of abacus) by David Bagley
Japan Chamber of Commerce and Industry and The League of Japan Abacus Association: Soroban