seven segment display history

[Rick Bensene]

I remember that seven-segment format being used in TTL(Time To
Launch)/MET (Mission Elapsed Time) on big signs by NASA in the early to
mid-1960's.
These were BIG digits that could be read from long distances.  The
segments were formed by putting together incandescent lights in rows and
columns, and a seven-segment rendition made the digits.  Also, many
sports scoreboards did (and still today) use a similar seven-segment
rendition using individual incandescent lamps to form segments.

Also, Brent mentioned the HP 9100A using a 7-segment rendition.  True,
but the much earlier (1963 versus 1968) Friden 130 used a seven segment
rendition on its CRT display.  It was slightly modified so that the "1"
was centered (by slightly shifting the deflection to the left a bit when
a 1 was displayed).  Also, a number of calculators introduced prior to
the HP 9100 utilized CRT displays with seven-segment renditions,
including the Victor 3900, and a couple of machines sold under contract
under the Busicom brand name, but designed and manufactured by Wyle
Laboratories (among them the Busicom 202), as well as Wyle Laboratories'
original WS-01 and WS-02 calculators.  These machines were all made
between 1965 and 1968.

The mission-control consoles of the 1960's and early '70's (before CRT
displays pretty much displaced discrete displays) typically used
projection-type displays, with small incandescent lights for each digit,
which would shine through a photomask of the shape of the digit, and be
focused on a frosted glass or plastic screen.  I had an old digital
clock years ago, using transistorized ring counters that used these type
of displays.  They were very readable, and nice, naturally formed
digits, with a nice white digit against at darker background.  The clock
was made in 1966 if I remember correctly.  Wish I still had that
thing...it ended up getting tossed out by my parents :-(


Rick Bensene
The Old Calculator Museum
http://oldcalculatormuseum.com