While playing around with trancendentals, it looks like RPN-32 can store a number like pi with 17 digits in any storage register. Looks like pi is stored as 3.1415926535897932. Same thing, if I enter such a number with the paste function. Nice level of accuracy !
I found that the latest update of the RPN-38 CX, along with RPN-32 CE for iPhone can now do that. It's especially nice when you run a program that requires several constants, that they can be saved with the program, along with the display settings (Fix 0-9 or Scientific) as well as the "Begin/End or D.MY/M.DY" switch on the HP-38C. And you can take a list of register contents from say an email and paste them into the calculator app. Also a programmable "RCL g R/S" for embedding an IRR command into a program.
A lot of neat features. Good thing I got our tax data to our CPA before this came out!
The latest update (June 2016) offers a live Register View. You can even single step in the register view so you can see what happens with each register as you SST. Can also R/S in the register view. Another nice feature is recall arithmetic on the Last X (e.g. RCL X Last X). I especially like that when saving programs to Dropbox I can also save constants. Really nice update to the two Spice series simulators (HP-32E & HP-38C). Likewise many similar additions to the HP-67 simulator for iPhone.