Panaplex display history

Johnny Billquist bqt at
Mon Jun 1 12:38:59 CDT 2015

On 2015-06-01 18:07, tony duell wrote:
>> 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.
> DEC used little modules containing an LED and series resistor that were
> the same size as the bi-pin T1+3/4 bulbs used earlier. In a CPU panel you
> had to clip out the pre-heat resistors, for obvious reasons. My 8/e is like that,
> although I think some 8/e's had bulbs. I've seen RK05s with bulbs and
> RK05s with LED modules. My 11/45 (I forget the serial number, it's early, perhaps
> 315) certainly has bulbs.

My 8/Es certainly have bulbs, while my 8/M and 8/F have LEDs.
I think I have RK05s with both bulbs and LEDs, while my RL02s are all bulbs.

> Thinking about it, I find it surprising that on later disk drives -- RL's, RK07s,
> R80s etc, they used bulbs and not LEDs. By that date LEDs were easily available and
> reliable.

I think it was just harder to replace the construction where you had 
push buttons with lamps. Those are not bi-pins.

The first "modern" drive that used LEDs that I can think of is the RA90. 
And then you didn't have the lamps in the buttons, but next to them, and 
then you had a 14(?)-segment 4 digit display to show more information.


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