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.
Johnny
