I think the count is up to 4 now, and with Johnny’s it makes 5, unless that one is already counted.

Hi,
Does it work? Do you have just the calculator or do you have a manual and box etc?
I have done quite a bit of work on the PRO-101, on one that had a broken RAM chip I replaced it with a RP Pico which fixes the problem and also gives the machine the ability to store programs in the flash of the Pico. There’s videos here:

https://youtu.be/Xrsssl8Ui9I
https://youtu.be/icZCyGyglA4
https://youtu.be/wefhQf8H8mM
https://youtu.be/QJGJ5JRpquA
https://youtu.be/w93zmpUBlWs
https://youtu.be/5b9_YsEz6IU

As the RAM is replaced with a Pico I was able to examine the internal structure of how programs are stored in the RAM, and the character codes used by the machine. You can display some alpha characters using the method of poking codes directly in the RAM.

I’ve put this sort of internal information here:

https://github.com/blackjetrock/casio-pro-101-info

I know only 2 Casio PRO-101 and both are located in France.
Contact Ledudu, he will be pleased to exchange his knowledge with you.