anchor.diff:  // This implementation uses a registered probe,
   // to hold the last value written to it.
   module mkAltSourceRProbe#(String id, tr initv, tw defv) (AltSourceProbe#(tr, tw))
  -provisos (Bits#(tr, sr), Bits#(tw, sw));
  +    provisos (
  +            Bits#(tr, sr), Bits#(tw, sw),
  +            Add#(pad, sr, TMul#(TDiv#(sr, 4), 4))  // by request of bsc
  +    );
  +
       AltSourceProbe#(tr, tw) child <- mkAltSourceProbe(id, initv);
       Reg#(tw) writeval <- mkReg(defv);
   
  
positive.code: // This implementation exposes a default value to the probe
  // during every cycle on which _write is not enabled.
  module mkAltSourceDProbe#(String id, tr initv, tw defv) (AltSourceProbe#(tr, tw))
  provisos (Bits#(tr, sr), Bits#(tw, sw));
      AltSourceProbe#(tr, tw) child <- mkAltSourceProbe(id, initv);
      Wire#(tw) writeval <- mkDWire(defv);
  
  
negative.code: // Its _write method needs to be enabled every cycle.
  import "BVI" AltSourceProbe =
      module mkAltSourceProbe#(String id, tr initv) (AltSourceProbe#(tr, tw))
      provisos (
              Bits#(tr, sr), Bits#(tw, sw),
              Add#(pad, sr, TMul#(TDiv#(sr, 4), 4))  // by request of bsc
      );
  
          parameter INSTANCE_ID = id;
          parameter SOURCE_WIDTH = valueOf(sr);
          parameter SOURCE_INITIAL_VALUE = " " +
  