;FILENAME:	UNIT15.TXT
;
; ASSEMBLY LANGUAGE COURSE, UNIT 15
; By Don Stoner Revision: 2008.07.20
;
; This program experiments with
; more graphical display formats.
;
	ORG 100h  ; Code Starts at 100h
	;
	; Same "Loop Back" trick:
	;
LOOP_BACK:	; Loop back to here
	CALL RUN_LOOP
	JMP LOOP_BACK	;from here
RUN_LOOP:
	;------------------------------
	; Output the same text:
	;
	CALL INLINE_ASCIIZ_OUT
	DB "CHARACTER TEST",0
	;
	; Draw a diagonal line made up
	; of points, with each point a
	; different color:
	;		;Starting:
	MOV CX,200	;X coordinate,
	MOV DX,200	;Y coordinate,
	MOV AL,200	;and Color
GRAPHICS_LOOP:	;draw 1 point per loop
	MOV AH,0CH ;Code to set 1 point
	XOR BH,BH    ;(use page 0)
	INT 10h	     ;Video interrupt
	;
	DEC CX	;Next pixel X coord.
	DEC DX	;Next pixel Y coord.
	MOV AL,DL   ;Set color from Y
	; Notice that color values are
	; limited to AL (0 - 255) This
	; means BIOS doesn't support
	; point-plotting for more
	; colors than 256. These need
	; direct writes to video RAM.
	JNZ GRAPHICS_LOOP ;Loop until
	;		      ;Y is 0
	; Fetch a key to tell the
	; program what to do next:
	;
	CALL ASCII_IN	;Read key to AL
	;
	; Select display depending
	; on which key was pressed:
	;------------------------------
	; VESA graphic modes:(AX=4F02h)
	;  Table of BX (in hex) 
	; colors:   16 256 32K 64K 16M
	; 320x 200  0D  13 10D 10E 10F
	; 640x 480  11 101 110 111 112
	; 800x 600 102 103 113 114 115
	;1024x 768 104 105 116 117 118
	;1280x1024 106 107 119 11A 11B
	;
	; "1" selects VESA mode 0Dh
	; 320x200 16-color graphics
	CMP AL,"1"
	JNZ NT1
	MOV BX,0Dh	;320x200,16
	MOV AX,4F02h	;VESA mode
	INT 10h	     ;Video interrupt
	RET	;Return to LOOP_BACK
NT1:	;
	; "2" selects VESA mode 13h
	; 320x200 256-color graphics
	CMP AL,"2"
	JNZ NT2
	MOV BX,13h	;320x200,256
	MOV AX,4F02h	;VESA mode
	INT 10h	     ;Video interrupt
	RET	;Return to LOOP_BACK
NT2:	;
	; "3" selects VESA mode 101
	; 640x480 256-color graphics
	CMP AL,"3"
	JNZ NT3
	MOV BX,101h	;640x480,256
	MOV AX,4F02h	;VESA mode
	INT 10h	     ;Video interrupt
	RET	;Return to LOOP_BACK
NT3:	;
	; "4" selects VESA mode 103
	; 800x600 256-color graphics
	CMP AL,"4"
	JNZ NT4
	MOV BX,103h	;800x600,265
	MOV AX,4F02h	;VESA mode
	INT 10h	     ;Video interrupt
	RET	;Return to LOOP_BACK
NT4:	;
	; "5" selects VESA mode 105
	; 1024x768 256-color graphics
	CMP AL,"5"
	JNZ NT5
	MOV BX,105h	;1024x768,265
	MOV AX,4F02h	;VESA mode
	INT 10h	     ;Video interrupt
	RET	;Return to LOOP_BACK
NT5:	;
	; "6" selects VESA mode 107
	; 1280x1024 256-color graphics
	CMP AL,"6"
	JNZ NT6
	MOV BX,107h	;1280x1024,265
	MOV AX,4F02h	;VESA mode
	INT 10h	     ;Video interrupt
	RET	;Return to LOOP_BACK
NT6:	;------------------------------
	; Escape?	(1Bh)
	;
	CMP AL,1Bh	;(Escape key)
	JNZ NTESC
	MOV AX,3     ;Restore normal
	INT 10h	     ;VGA mode 3
	INT 20h	     ;And return to DOS
NTESC:	RET
;--------------------------------------
%INCLUDE "UNIT11.ASM"	;(Subroutines)