Panaplex display history

[Brent Hilpert]

On 2015-May-30, at 8:19 AM, tony duell wrote:
> 
>> JOOI, does anyone know when Panaplex 7-segment displays started going the
>> way of the dodo, to be replaced with LED displays (and, on the back of
>> that, what were the advantages of a Panaplex-type display over an LED one?)
> 
> It would appear that in the early 1970s LEDs were very expensive. I have been looking at the 
> HP5930x HPIB units and in many cases the status indicators (power on, listening, etc) are 
> filament bulbs + driver transistors. I can think of no advantage to using a filament bulb in this
> application other than possibly cost. The 59304, which has a Panaplex display and therefore
> the HV supply to drive it, uses neon bulbs (NE2 sort of thing) as status indicators.

And the annoying and inconsistent use of incandescent bulbs for the power indicator and optical tape detector in the 9830 . . when the main display is LED.