Amazingly, the HiSoft C++ compiler works completely under OS4.1 update 5. The installer does not work in OS4 because LHX does not work...I installed the program using the WB3.1 emulation via RuninUAE. Then, copy L:hothelphandler and L:hotkeyhelphandler to your OS4:L directory from your OS3.1:L directory, and copy Libs:rtc.library as well as libs:hothelp.library. If you installed it for english language, you must also copy locale/catalogs/english/maxondev.catalog to your OS4:locale/catalogs/english directory from your OS3.1 as well. Note that all programs I tried worked and compiled just fine in HiSoft C++ 4.1 (21.10.97), including helloworld.c and colorwheel.c. You are compiling 68k programs