{
  TMapFile::SetMapAddress(0x4125c000);
  TMapFile* mfile = TMapFile::Create("hsimple.map","RECREATE", 100000,
                            "Demo memory mapped file with histograms");
  
   TH1F* hpx    = new TH1F("hpx","This is the px distribution",100,-4,4);
   
   hpx->SetFillColor(48);

   mfile->Print();

   Float_t px, py, pz;
   int ii = 0;
   while (1) {
     gRandom->Rannor(px,py);
     hpx->Fill(px);
     if (!(ii % 10)) {
       mfile->Update();       // updates all objects in shared memory
       if (!ii) mfile->ls();  // print contents of mapped file after
     }                         // first update
     ii++;
     gSystem->Sleep(100);
   }
}