HGA access ?

[F. Draeger]

Hi,
	I'm running SCO XENIX using a Hercules Graphic adapter and
	would like to write a graphic library.
	Writing directly to the control ports of the graphic card
	caused a memory fault ( I assune, that these memory areas
	are protected and only used by the kernel ) .
	I found some special devices like :

		/dev/mono
		/dev/monochrome

	Redirecting stdout to these devices send my output to
	the screen .
	Are there any possibilities to have graphic access through
	these devices or in any other way ?

	Should I have to write a new device driver and how should this
	be done ?


	Thanks for posting me Your ideas and/or solutions ....

			Greetings,
				    Frank Draeger