chmap_cls
	;di
	ld (chmap_old_cls_sp),sp
	ld hl,chmap_old+chmwid
	ld de,BLANKCHUNK*#0101 ;#fefe ;0+(chmap_old/256)*#101
	ld b,chmhgt
chmap_old_cls0
	ld sp,hl
	dup chmwid/2
	push de
	edup
	inc h
	djnz chmap_old_cls0
chmap_old_cls_sp=$+1
	ld sp,0
	;ei
	ret
