anchor.diff:  
   ==== Command ====
   ---------------------------------------
  -0x47 0x44 0x43 0x00 0x00 0x00 0x00 0x0?
  +0x47 0x44 0x43 0x00 bank 0x00 0x00 checksum
   ASCII: "GDC" (Get Data Count?)
  +index = 0..(value returned by GDC - 1)
  +bank = 0x00, 0x01 or 0x02, perhaps for user A, user B, combined?
  +checksum = the XOR of the bytes after "GDC"
   ---------------------------------------
   
   ==== Parameters ====
  
positive.code: ==== Output Report Example in HID Raw Report Format ====
  ---------------------------------------
  0x05 0x50 0x52 0x46 0x30 0x30 0xXX 0xXX
  ---------------------------------------
  
  ==== Return Example ====
  ------------------------------------------------------
  0x30 0x30 0x31 0x30 0x31 0x30 0x30 0x30 0x30 0x30 0x00
  (ASCII: '00101000')
  ------------------------------------------------------
  
  ==== Return Example in HID Raw Report Format ====
  
negative.code: 	 - 0x2X - Second reading of a 3 reading average (TruRead function)
  	 - 0x3X - Third reading of a 3 reading average (TruRead function)
  	 - Others: UNKNOWN
  Byte D:: Checksum (XOR of bytes 0..C)
  
  ==== Output Report Example ====
  Command gets newest available record
  