The Gomez DOS Extender is the base for many other projects in the discontinued projects section. It provides a true 32bit flat memory model in DOS for assembler programs and supports RAW/XMS and VCPI-mode. Unfortunately it does not support DPMI, so all programs that use this DOS extender won't work with Windows.
In order to get the code compiled, you will need the Turbo Assembler from Borland.