Purpose Clear the screen and draw lines down the right and left sides of the screen.
Code
disp_sidelines:
	call _clrLCD		;clear the screen
rows_down	=3		;start lines
				; this many rows
				; down the screen
	ld a,64-rows_down	;how many rows down
sideline_loop:
	ld hl,side_bar_graphics	;graphics for one line
				; with the side bars
	ld bc,$10		;one line
	ldir			;copy that one line
	dec a			;we're using a as our
				; counter since b
				; is used with ldir
	jr nz,sideline_loop
	ret
side_bar_graphics:		;graphics to copy over
				; and over and over
	.db %10000000, 0, 0, 0, 0, 0, 0, 0	;left
	.db 0, 0, 0, 0, 0, 0, 0, %00000001	;right
	
Error We need to rewrite the entire routine. Sometimes we want to have something written at the top of the screen, we won't want that cleared. That takes our the _clrLCD.

Let's still keep ldir but make it copy the first line (which probably is zeroed) over and over all the way down the screen.

We save 15 bytes! Not to mention lots of clock cycles.

Fixed Code
rows_down	=3		;rows down from top
				; to start at
rows_up		=5		;rows up from bottom
				; to end at
left_side	=%10000000	;what left side looks
				; like
right_side	=%00000001	;what right side looks
				; like
disp_sidelines:
	ld hl,$fc00+(rows_down*$10)	;starting row
	ld de,$fc00+(rows_down*$10)+$0f	;end of first row
	ld (hl),left_side		;left graphic
	ld a,right_side			;right graphic 
	ld (de),a
	inc de				;new row
	ld bc,$0400-((rows_down+rows_up)*$10+$10)
					;# bytes to end
					; of screen
	ldir
	ret