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XLED - A LED server for LAM

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XLED is an X/Motif based client/server package that emulates hardware LEDs. It is implemented on top of LAM, a cluster computing environment for UNIX. It provides a low cost alternative for sexy blinking LEDs demos (popular with supervisors and managers!) and quick-n-dirty debugging.

The XLED client library can be used by MPI applications under LAM, from C and Fortran. It provides a simple interface to turn on/off selected LEDs and inquire about their current state. The XLED server can be run on any node in the LAM multicomputer. The LED calls locate and direct their requests to the proper destination.


  • lam_ledinit( ) handles initialization.
  • lam_ledclr( ) clears the LEDs.
  • lam_ledon( ) turns on an LED.
  • lam_ledoff( ) turns off an LED.
  • lam_ledisset( ) checks the state of an LED.
  • lam_ledgetnum( ) gets the number of LEDs.

How to Get XLED

XLED was developed at the Ohio Supercomputer Center and is freely available under a GNU license from the LAM download site.