Andy.....Have you not heard of the 32-bit DOS Extenders for '386+ computers. A package for one such development environment sits on the shelf above my computer called "The PHAR LAP DOS Extender". This is the type of environment of which Mr Simonsen speaks. There are one or more open source environments of this type too.

Programs written in these environments will launch under true 16-bit DOS and switch over to 32-bit mode on '386+ processors. The environment provides methods to permit thunking down to DOS mode to support DOS and BIOS calls.

The later and more robust versions of these DOS extenders, including the one that shipped with the Borland BC++ 4 & 5 versions as the "DOS Turbo Power Pack" had the ability to check if a Windows 32-bit environment was already loaded and interface to that instead of its own thunker!

There was much much need for large > 640K programs long before Windows hit the streets big time!!!

Michael Karas