Pdp 11/20 front panels

From: Chad Martin <chad.martin_at_fli-invent.com>
Date: Fri Feb 27 13:40:27 2004

I own an early 11/20, sn300, also of the PDP-11 only markings, like the unit
in question. My front panel PCB is date stamped 1970, and it is the led
type. I also have original DEC schematics that show first bulbs, and then a
revision to allow bulbs or LEDs. I also have some other front panel PCBs
with bulbs.

My best guess would be that they did a revision for LED's, and then perhaps
dropped them due to cost or availability. So it appears that LEDs were at
least installed on some 11/20s.

My LED unit does not have the front panel drilled out, but I suppose they
may have done that for one of the early proto types while they were trying
different designs.

My 11/20 was supposed to have been gotten from the dec Mill factory in Mass,
perhaps the early LED units were never shipped out. So it is likely that
the 11/20 for sale is for real.

Chad Martin
Received on Fri Feb 27 2004 - 13:40:27 GMT

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