)
Values for DR DOS memory space control error code:
 00h	successful
 80h	video memory already unmapped
 81h	video memory already mapped
 82h	no video memory reserved (/VIDEO not specified)
 83h	video memory in use (graphics mode or non-standard text mode)
 84h	mapped video memory contains allocated arena(s)
 85h	hardware error
 86h	driver requires protected mode but is permanently in real mode
	  ("EMM386 OFF")