Back in the nineties when I began studying, my class in Control and Instrumentation Practical Engineering at Ruppin College in Israel decided, as a class, to use the HP48GX. It was a great decision. Up until then, they'd been using some crappy Casio programmable calculator - not even in the same league.
But anyway, I purchased your fine book, An Easy Course in Programming the Hp48Gx , and it helped me immensely in gaining mastery over that amazing late machine, the HP48GX, RIP.
Fast forward 22 years, and once again I need a calculator. My 48 has died and HP has discontinued the 48-50 series, so I now own the HP Prime Graphing Calculator. HP has, with the Prime, reinvented the wheel, and their User Manual just doesn't cut it.
Would you be willing to consider writing a new book about the HP Prime? I, for one, would be very grateful.