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.
Johnny
