HP-42S LinksFree42 - HP-42S Calculator Simulator
Thomas Okken's implementation of the HP-42S for a wide range of computers and operating systems. This software does not require any HP ROM images and was written from scratch by Thomas Okken. The programs and source code is available for free from his site. He also has a good selection of HP-42S programs available.The Museum of HP Calculators
This site contains a wealth of information on the Hewlett-Packard calculators from the period of 1968 to 1986. There is extensive information on each calculator model complete with pictures. The site is also a source for documentation, including manuals. Also check the Links page for more links to HP and calculator related sites.Hewlett-Packard Calculators
Eric Smith's implementation of a microcode level simulator of a number older HP calculators. It runs mainly on Linux/Posix/Unix systems with some support. The Links page also contains some interesting links.hpcalc.org
This site is about HP-50, HP-49, HP-48, and HP-28 RPN calculators and the HP-38G, HP-39, and HP-40 programmable graphic calculators. It is a good source of information as well as software for these calculators.