   byte cmd = parseCommand();
   int bytes = 0;
   switch(cmd) {
+  case SET_ADDRESS:
+    // Set the address bus to an arbitrary value.
+    // Useful for debugging shift-register wiring, byte-order.
+    // e.g. A,00FF
+    Serial.print("Setting address bus to 0x");
+    Serial.println(cmdbuf + 2);
+    set_address_bus(startAddress);
+    break;
   case READ_HEX:
     //set a default if needed to prevent infinite loop
     if(lineLength==0) lineLength=32;

  lineLength=hexByte(cmdbuf+12);
  byte retval = 0;
  switch(cmdbuf[0]) {
  case 'R':
    retval = READ_HEX;
    break;

//define COMMANDS
#define NOCOMMAND    0
#define VERSION      1
#define SET_ADDRESS  2

#define READ_HEX    10
#define READ_BIN    11
