$B0-$B1/176-177:   Tape timing Constants

  Used by Jiffy-DOS: SPRSAV ($B0)
  Used by Jiffy-DOS: RASSAV ($B1)

   Saved, then restored by Load routine (no other usage).

  Used by Jiffy-DOS: KEYPTR

   Used only from Basic for Jiffy-DOS wedge comands, device
   toggle and function keys.