Panaplex display history

Johnny Billquist bqt at
Mon Jun 1 10:36:19 CDT 2015

On 2015-06-01 17:31, Jon Elson wrote:
> On 06/01/2015 04:03 AM, Christian Corti wrote:
>> On Sat, 30 May 2015, Jon Elson wrote:
>>>> Is there a good reason why filament lamps were used on minicomputer
>>>> front panels until the mid 1970s? Things like the PDP11/45, Philips
>>>> P850, etc
>>>> all used filament bulbs, not LEDs.
>>> Inertia!  The 11/45 was designed before LEDs were available, and so
>>> they never changed.  To do it right, the PC board would have to be
>>> re-designed to
>> Hold on! Most 11/45 have LED frontpanels (such as mine from 1974). The
>> earlierst ones might have bulbs, but they switched to LEDs during
>> production.
> OK, I know 11/70's had LEDs, but all the /45's I worked with had bulbs.
> Ours was SN 343, which I guess must have been an early unit.  We got it
> used in 1976 or possibly 1977, and it looked pretty "well used" when we
> got it.

Thinking about it, I seem to remember seeing some picture of an 11/70 
with bulbs as well, but all 11/70 machines I've seen or worked on had 
LEDs, so I suspect they might have had bulbs initially as well.


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