DOS extender
The incomplete DPMI implementation and the lack of support for virtual memory (demand paging, swapping, etc.) are reasons why PMODE may not be a suitable for some applications. PMODE was entirely written in x86 assembly language, and early versions were not directly usable by programs written in high level languages (including C). The price of PMODE/W may have been a deterrent to some, although most other DOS extenders at the time commanded a comparable or higher price (such as the Phar Lap DOS extender).