I have written some software for the HP49G and HP49G+ calculators, a
book about SystemRPL, and a database of SystemRPL and ML entry
points. Much of this is also available from the HP48 Software Archive.
Programming in System RPL
Together with Eduardo M. Kalinowski I have written a
600+ pages book on how to program the HP49G in System RPL. The book
is freely available, and you can just download it here. A separate file
contains the example programs used in the book.
The entry database is a list of about 7000
SystemRPL and ML entry points which can be used to program the HP
calculators 38G, 39G, 48G, and 49G.
Emacs Emacs is an extension to the built-in editor of the
HP49G. It provides Editor and development support on the HP49G and
integrates several libraries and built-in tools into a full
development environment. The current Emacs version is 2.10.
For details and download, check this page.