anchor.diff:     Bit#(ByteEnableSize) firstbe; // maybe we only need lastbe
      Bit#(ByteEnableSize) lastbe;
   `endif
  -   } MemRequest deriving (Bits);
  +   } MemRequest deriving (Bits, FShow);
   
   instance DefaultValue#(MemRequest);
      defaultValue = MemRequest {
  
positive.code:    Bit#(dsz) data;
     Bit#(MemTagSize) tag;
     Bool last;
     } MemData#(numeric type dsz) deriving (Bits);
  
  typeclass ReqByteEnables#(type t, numeric type besz);
     function Bit#(besz) reqFirstByteEnable(t req);
  
negative.code:    Bit#(TDiv#(dataBusWidth,8)) firstbe; // maybe we only need lastbe
     Bit#(TDiv#(dataBusWidth,8)) lastbe;
  `endif
     } PhysMemRequest#(numeric type addrWidth, numeric type dataBusWidth) deriving (Bits, FShow);
  
  instance DefaultValue#(PhysMemRequest#(addrWidth,dataBusWidth));
     defaultValue = PhysMemRequest { addr: 0, burstLen: 0, tag: 0
  