Hello thank you for taking time to read my thread. My former boss Tim Rogan has passed away and in my eyes was a borderline genius in the machine world. He could do it all and truly had a passion for it. He taught me so much last year when I started working for him. Tim recently passed away and left his son the shop. We want to run it in his honor and because the works very enjoyable and want to pick up where Tim left off. Sadly he was the mastermind behind our g code on our ancient machines. His son has tasked me with learning g code for these older machines. I figured the forums would be a good place to start. I would appreciate some recommendations on what type of approach I should take to learning these machines and g code in general. I can understand it for the most part but putting a print into code is another story. Questions and machines I need to learn g code for first are listed below.

What programs if any would cater to these old machines?

What websites, resources, books, videos do you recommend?

What kind of homework, quizzes or things should I do to test myself outside of the shop?

Any recommendations at all? Especially if you are or have been familiar with any of the three machines listed below.

Machines
YAM CK 2 with Fanuc 6t control

Sheldon Mill unsure of control but can get name next time I'm in the shop. It's old see pics. Still works great though.

Unknown lathe until I get into shop again with Omniturn control