Salvador Parra Camacho has ported ehm 0.6 to OS/2-eCS. The port requires QT4 libraries installed
"ehm is a simple calculator (QT4)"
The download file includes the binaries and source code:
Hobbes: http://hobbes.nmsu.edu/h-search.php?key=ehm06-os2.zip
Official Web Site: http://code.google.com/p/ehm/