[time-nuts] purpose of time of day display units

[Ruslan Nabioullin]

On 01/22/2017 07:26 PM, Hal Murray wrote:
> Many years ago, I designed network gear.  That was back when a controller was
> a board full of small and medium sized chips rather than a single big chip.
> I always put a few LEDs on the board wired up where the microcode could get
> at them.  Most of the time they were just eye candy.  But occasionally I
> would borrow one and hack the microcode so a LED would be interesting on a
> scope.

Ah, just like those status LEDs on PCBs, subsystems, and modules in 
properly-engineered equipment (both old and modern minicomputers, 
aerospace equipment, VME and VXI systems, some other servers [some of 
HP's small servers, at least, even feature a neat diagram on the front 
panel, with status LEDs indicating the status of key subsystems or 
components thereof], etc.)  Apple's hardware obviously is an offender in 
this regard---I remember once having to service an iMac (or some other 
modern Apple PC), and I seriously could not figure out how to turn it 
on, and when I had to temporarily shut off the power distribution 
system, I could not figure out what the PC's power state was (to ensure 
a graceful shutdown of the system).

-Ruslan