viddata.inc

MMURTL(tm) Computer Operating System Ver x0.8, source code.

;   MMURTL Operating System Source Code
;   Copyright 1991,1992,1993, Richard A. Burgess
;   ALL RIGHTS RESERVED
;   Version x0.8

;This is the data module for the virtual character video service.
;The video code is fully reentrant because each job has it's own
;video screen.  Only one of these screens will be the active video
;display.
;
;Video Equates and Types
;
CRTCPort1   EQU 03D4h	;Index port for CRTC
CRTCPort2   EQU 03D5h	;Data port for CRTC
CRTCAddHi   EQU 0Ch	  	;Register for lo byte of Video address
CRTCAddLo   EQU 0Dh		;Register for lo byte of Video address
CRTCCurHi   EQU 0Eh		;Register for lo byte of Cursor address
CRTCCurLo   EQU 0Fh		;Register for lo byte of Cursor address
CRTC0C	    DB 0	   	;CRT Reg 0C HiByte address value
CRTC0D	    DB 0	    ;CRT Reg 0D LoByte address value

VGATextBase EQU 0B8000h ;Offset from OS DS to VGA Text screen 0

ddVidOwner	DD 1		      	;JCB that currently owns video
								;Default to monitor (Job 1)