Casio Tsumego Calculators
Back in the 1980s, Casio came out with the TG-1 and TG-2 Electronic Calculator. TG-1 was not a calculator but only a handheld electronic tsumego game. The TG-2 included a calculator as well as all the functions of the TG-1. The TG-2 also has a contrast dial to adjust the contrast of the LCD screen. The above picture is part of a catalogue from 1985.
These gadgets came with the TP-11 Tsumego ROM which held 100 problems (40 beginners, 40 Intermediate, and 20 Advanced) by 3 Japanese pros. Each problem is for Black to solve. You can input the coordinate of the place you would like to place a stone and then either “check” it for a hint or “set” it if you think it is correct. The computer will play the next move or let you know if you are correct “Good” or will tell you to “Try again”. Once solved, you can replay the moves forwards and backwards. You can go to the next problem via the search function (left/right arrows) or via direct input of the level and problem number.
I was fortunate to be able to purchase a TG-2 shown below.
There is an optional ROM called the TP-10 which presents even more problems of the “Best Next Move” (次の一手) variety. I do not have this ROM but have included a picture I found of it below from an auction where the set was bid to quite a sum.