Free42 v2.0.24 is released. Free42 is a complete re-implementation of the HP-42S scientific programmable RPN calculator,was made from 1988 until 1995 by Hewlett-Packard and the HP-82240 printer. Free42 was written from scratch, without using any HP code. You do not need any ROM images in order to use it, yet it is fully HP-42S compatible.

http://thomasokken.com/free42/