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CONTRIBUTIONS/z80em86/support/video.mac

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+;**************************************************************************
+;*                                                                        *
+;*          VIDEO v1.00 turns video ON or OFF  S.J.Kay 22/04/95           *
+;*                                                                        *
+;*                       Support utility for CP/M 3                       *
+;*                                                                        *
+;**************************************************************************
+
+	maclib	TPORTS.LIB
+;
+	.z80
+	aseg
+;
+	org	0100h
+	.phase	0100h
+;
+	ld	b,0			;video on value
+	ld	hl,0080h		;parameter address
+	ld	c,(hl)
+	inc	hl
+chkchr:	ld	a,c			;characters to check
+	or	a
+	jp	z,video1
+	ld	a,(hl)			;get a character
+	dec	c
+	inc	hl
+	cp	' '			;ignore any leading spaces
+	jp	z,chkchr
+	cp	'O'			;1st character must be 'O'
+	jp	nz,video1
+	ld	a,(hl)			;2nd character
+	cp	'F'			;video off if 2nd char is 'F'
+	jp	nz,video1
+	dec	b			;video off value
+video1:	ld	a,b
+	out	(vidset),a		;turn video on/off
+	ret
+;
+	.dephase
+	end