Gregory's Server
In the extremely unlikely scenario that you, like me, might need a little graphical desktop #abacus, I made this tiny thing(1.2kb) to help me with homework.
Download: https://rabbits.srht.site/soroban/soroban.rom
Source: https://git.sr.ht/~rabbits/soroban
Enjoy!
I've been enjoying this book a lot.
Takashi Kojima's Advanced Abacus, incidentally it describes something very similar to the Karatsuba algorithm in the alternative multiplication techniques.