Insight Amusement

[Jay Ashworth]

Ganked from Facebook:

"""
From the inside of an ETC Insight 3 lighting console... this has been included in every console they made for several decades. It used to be populated with an actual connector, in later models they stopped bothering. Apparently the story is that it was for a planned output module that either never got made or never sold very well, but the guy responsible left the company, and it kept getting included in every PCB design after that because despite nobody knowing what it did, they figured it was safer to leave it in case someone somewhere WAS using it.
"""

 

[FMEng]

Great story, but more likely a test port to make quality control testing easy.

 

[TimMc]

Great story, but more likely a test port to make quality control testing easy.

I'm thinking that it would have had a pin header installed - multi layer board, etc.

 

[Malabaristo]

I'm thinking that it would have had a pin header installed - multi layer board, etc.

If you needed a pin soldered in the hole to make connection to all the layers, then you wouldn't have a reliable connection even with a pin soldered in. The plating on the hole is what makes the electrical connection between layers, so theoretically you could use it as a test point whether or not a connector was soldered in. That said, I can confirm it was not used as part of the test process (QC or repairs). I'm not quite old enough to have been around for the early days of those consoles, but my understanding basically matches what Jay said: it was for possible future expansion that was never implemented and became kind of an inside joke. It would have cost more to remove it from the design of later boards (after it was clearly going to remain mythical) than it did to leave it alone.

Also, it wasn't so much that they stopped bothering in newer consoles, but with introduction of the Eos family, everything standardized on USB for interconnects rather than proprietary parallel busses. That went along with choosing commodity motherboards and other PC parts to simplify the development process and provide a big jump in capabilities. It also helped avoid a recurrence of the Express/ion software problem where it became impossible to make any further improvements after hitting the brick wall of hardware limitations. You can still hit limits as specific hardware ages (the XP-based versions, for example), but moving forward is much less involved than it was in the days of a completely custom operating system written for a very specific processor.

 

[TimMc]

The same thing happened in audio mixers, a couple decades later. LX got in early.

Jerry Pournel cynically called it "real soon now" when writing about computers. Mythical Bus seems remarkably candid.

 

[Jay Ashworth]

I'm not quite old enough to have been around for the early days of those consoles, but my understanding basically matches what Jay said: it was for possible future expansion that was never implemented and became kind of an inside joke.

Though I was quoting the guy who posted the pic to Facebook, whence I ganked it.