RPN-65 Question.

[Steve Simpkin]

(08-20-2023 08:58 PM)Matt Agajanian Wrote:  Steve, thanks for the repeat of the info about the Woodstock series. Very appreciated and illuminating.

Matt, No problem I learned something new to me. I did not realize that the HP-65 used storage register 9 for trig functions. So did the HP-45. The HP-55 on the other hand, did not appear to need any stack or register location for trig functions.

According to Eric's HP Calculator Memory Sizes site, the HP-55 had 30 RAM registers total. Of these 20 were used for storage registers R0-R.9, 1 for Last X and 7 for the 49 program step storage. This left 2 registers left over that were not available to the user. It appears they used one of these for trig functions. I am not sure if the other leftover RAM register was used for anything (maybe the timer?).