Assembly Problem

I've recently been working on a little bit of assembly programming, using the Masm assembler, and decided to try a little program in mode 13h. I wanted it to draw alternating black and white squares in a tile-like pattern. Well, I got the code to work, but everytime I assemble it, it gives me a random line that is all black. Here is the source code:

.MODEL SMALL
.STACK
.DATA

x dw 0
y dw 0
go dw 0

.CODE

MAIN PROC
	mov ax,13h		;This sets the screen into mode 13h
	int 10h

	;########################
	;color = white

	mov cx, 25
	program:
		mov go,0
	
		push cx
		mov cx,4
		line:
			push cx
			mov cx,40
			top:
				push cx
				mov cx,4
				white:
					mov ah, 0Ch		;Draws a dot in the middle of the screen
					mov al, 31			;Sets color

				    	mov  di, 0A000h   		;draw the pixel
				    	mov  es, di      
					push ax  
    					mov  ax, 320     
    					mul  y         
    					mov  di, ax    
					pop ax   
    					add  di, x  
    					mov  es:[di], al    	       	;done drawing the pixel
   	           
					inc x
				loop white
				mov cx,4
				black:

					mov ah, 0Ch		;Draws a dot in the middle of the screen
					mov al, 16			;Sets color
	
    					mov  di, 0A000h   		;draw the pixel
    					mov  es, di      
					push ax  
    					mov  ax, 320     
    					mul  y         
    					mov  di, ax    
					pop ax   
    					add  di, x   
    					mov  es:[di], al    
   	           
					inc x
	
				loop black

				pop cx

			loop top

			mov x,0
			pop cx
			inc y

		loop line

		program1:
	
		cmp go,1
		je program

		mov cx,4

		line1:

			push cx
			mov cx,40
	
			bottom:

				push cx

				mov cx, 4

				black1:

					mov ah, 0Ch		;Draws a dot in the middle of the screen
					mov al, 16			;Sets color
	
    					mov  di, 0A000h   		;draw the pixel
    					mov  es, di      
					push ax  
    					mov  ax, 320     
    					mul  y         
    					mov  di, ax    
					pop ax   
    					add  di, x    
    					mov  es:[di], al    

					inc x

				loop black1

				mov cx,4

				white1:

					mov ah, 0Ch		;Draws a dot in the middle of the screen
					mov al, 31			;Sets color
	
    					mov  di, 0A000h   		;draw the pixel
    					mov  es, di      
					push ax  
    					mov  ax, 320     
    					mul  y         
    					mov  di, ax    
					pop ax   
    					add  di, x     
    					mov  es:[di], al   

					inc x

				loop white1
	
				pop cx

			loop bottom

			mov x,0
			pop cx
			inc y

		loop line1

		pop cx

	mov go,1
	loop program1	
	
	;///////////////////////////////////////////////////////


	mov ah,07h		;Waits for a key press
	int 21h

	mov ax,03h		;Sets the screen back to text mode
	int 10h

	mov   ax,4c00h                      	 ;exit (no error)
	int  21h

MAIN ENDP
END MAIN

So, I have two questions: Why does it give me the random black line? and The assembler gave me an error when I looped from the bottom all the way up to the top, it said the distance was too far. Why would this be and is there any way to fix that other than what I did (set it to jump to another point in the middle of the program, then to the top)? Any help is greatly appreciated! [edited by - eriel on August 5, 2003 6:16:00 PM]