Here is a copy of the code with bug:

LVerLine: clr	Select
          mov	r3,  #0b8h      ;start with first page
VerLup1:  mov	a,  #40h	;problem here...
     	  call	Write_Instr     ;1st Column CS1 
     	  mov	a,  r3          ;page address
     	  call	Write_Instr     
     	  mov	a,  #0ffh
     	  call	Write_Data
     	  mov	a,  #0ffh
     	  call	Write_Data
     	  inc	r3              ;next page now
     	  cjne	r3, #0c0h, VerLup1
     	  ret

The problem got solved by just shifting the Column address write instruction AFTER the page address write instruction.

One reason I can guess is that whenever you change the page the Y-Address is at the starting point. And when you ALSO try to write #40h again the Y counter is incremented once.

(Incidentally is there any Patenting procedure for such "discovery" ? ;-) )


Raghu