There are 4 LEDs on the CopperRocket; the printing on the metal enclosure
labels them "Power", "LAN", "DSL" and "Data" from left to right.  All 4 are
identical in hardware and controlled purely by software though; each LED can be
lit green, red, orange or off.  (There are actually two LEDs under each lens,
green and red.  Orange is produced when both are lit simultaneously.)

The following LED usage convention has been established on the Hack-o-Rocket:

* The monitor lights the power LED green and all others off when it's done with
  the basic system initialization and awaits operator commands.

* The RAM-based monitor / flash writer utility lights the power LED orange and
  all others off when it runs.

* When an exception or interrupt traps to the default handler installed by the
  monitor (i.e., not handled by the application), the power LED is lit red and
  all others off as a diagnostic message is printed and the user is dropped
  into the monitor.

* The IP router (operational code) lights the power and data LEDs green
  continuously to indicate that it's running.  The LAN LED is lit green or off
  based on whether or not the CS8900 Ethernet chip reports 10BaseT link up.
  The DSL LED is lit different colors based on the ASM state on the SDSL
  version or based on the U interface state as reported by the ISDN chip on the
  IDSL version.
