At power-on or reset time, you must initialize one of the Copper
 location registers (COP1LC or COP2LC)  and write to its  strobe address 
before Copper DMA is turned on. This ensures a known start address and
known state. Usually,  COP1LC  is used because this particular register is
reused during each vertical blanking  time. The following sequence of
instructions shows how to initialize a  location register . It is assumed
that the user has already created the correct  Copper instruction list  at
location "mycoplist."

;
; Install the copper list
;
     LEA     CUSTOM,a1           ; a1 = address of custom chips
     LEA     MYCOPLIST(pc),a0    ; Address of our copper list
     MOVE.L  a0,COP1LC(a1)       ; Write whole longword address
     MOVE.W  COPJMP1(a1),d0      ; Causes copper to load PC from  COP1LC 
;
; Then enable copper and raster dma
;
     MOVE.W  #(DMAF_SETCLR!DMAF_COPPER!DMAF_RASTER!DMAF_MASTER),DMACON(a1)
;

Now, if the contents of  COP1LC  are not changed, every time
 vertical blanking  occurs the Copper will restart at the same location
for each subsequent video screen. This forms a repeatable loop which, if
the list is correctly formulated, will cause the displayed screen to be
stable.