🚀 go-pugleaf

In article <JET.92Nov17104503@boxer.nas.nasa.gov> jet@boxer.nas.nasa.gov (J. Eric Townsend) writes:
>Blinking lights.  Lots and lots of blinking lights....

Ah, yes, blinking lights.  The first parallel machine I worked on  (C.mmp,
a collection of 16 PDP-11s built at Carnegie-Mellon in the 1970's) had
a pretty fair collection of blinking lights, and looked pretty when
you turned the computer room lights off.  Not only did each PDP-11 have
a front panel with a row of lights, the crosspoint interconnection for the
shared memory had 256 lights, one for each crosspoint.  I have forgotten the
original rationale for putting those lights on the crosspoint, but we
actually diagnosed some memory conflict performance problems by watching the
lights while an application ran.  In addition, the "I'm dead" error routines
from the processors were written to make particular patterns on the front
panel of the PDP-11s.

However, current systems have other methods for getting similar information.
Other than being a designer preference for "flash" vs "cool", what benefits
do lots of blinking lights offer, and what should they represent?
I.e. Do people have suggestions for specific hardware events that might
be connected to blinking lights on a massively parallel shared memory super?

- Patrick McGehearty