New Checksum Check

ChecksumCheck:
        xref    Checksum
        moveq   #0,d0           ; clear checksum cnt
        lea     $200.w,a0       ; check from $200 until ROM's end
        move.w  #((((ROMSz*$100000)-$200)/2)/2/4/8)-1,d7

.loop   rept    2*4*8           ; do =$80 bytes per loop
        add.w   (a0)+,d0        ; add word to checksum cnt
        endr
        dbf     d7,.loop
        cmp.w   Checksum.w,d0   ; does result match to expected checksum?
        beq.s   .0              ; if yes, branch

.ChecksumError:
        move.l  #$C0000000,vdp_control_port
        move.w  #cRed,vdp_data_port
        bra     *
.0