**************************************************
* System Call: F$CRCMod
*
* Function: Changes CRC module reporting
*
* Input:  A = Flag (0 = report, 1 = CRC off, 2 = CRC on)
*
* Output: A = State (0 = CRC off, 1 = CRC on)
*
* Error:  CC = C bit set; B = error code
*
FCRCMod  lda    R$A,u       do they want a report or a toggle?
         beq    CRCRep      a report only
         deca               check for OFF
         bne    GoCRCon     no, must be on
         fcb   $8C          skip 2 bytes, saves 3 bytes of memory
GoCRCon  lda    #$1         CRC checking on
         sta    <D.CRC      turn CRC checking on
CRCRep   lda    <D.CRC      get current CRC flag for return
CRCRep2  sta    R$A,u       save it to their register stack
         clrb               no error 
         rts                and exit