Punch cards have been used in computer systems since the very early days of
digital programming. They were probably the first form of read-only memory (ROM), come to think of
it. I hate to have to admit it, but the meager computer used in my high school
computer lab (circa early-mid 1970s) used punched cards. I never took the class,
but stories abounded of how pranksters would shuffle a stack of punch cards
while the student programmer wasn't watching and then get a good laugh when
nothing worked. There are also plenty of cases where a stack was inadvertently
knocked onto the floor and had to be laboriously re-ordered. IBM is the brand
that comes to most people's minds when thinking about the old punched card
computer systems, but other companies like
NCR (National Cash
(Digital Equipment Corporation), and plenty of others others played in the
realm. This advertisement from Bell Telephone Laboratories boasted of their
automated call routing computer system that used a punched card programming
technique to optimally connect telephones from point A to point B in the least
amount of time. It was ground-breaking at the time, which was 1955.
Bell Telephone Laboratories Ad
How your telephone call asks directions ... and gets quick answers
Perforated steel cards, which give directions to the Long Distance dial telephone
system, are easy to keep up to date. New information is clipped (l) and punched
(2) by hand on a cardboard template. This guides the punch-press that perforates
a steel card (3), and the two are checked (4). The new card is put into service
in the card translator (5).
When the Bell System's latest dial equipment receives orders to connect your
telephone with another in a distant city, it must find - quickly and automatically
- the best route.
Route information is supplied in code - as holes punched on steel cards. When
a call comes in, the dial system selects the appropriate card, then reads it by
means of light beams and photo-transistors. Should the preferred route be in use
the system looks up an alternate route.
It is a simple matter to keep thousands of cards up to date when new switching
points are added or routing patterns are changed to improve service. New cards are
quickly and easily punched with the latest information to replace out-of-date cards.
This efficient, flexible way of keeping your dial system up to the minute was
devised by switching engineers of Bell Telephone Laboratories, who are continually
searching for ways to improve service and to lower costs. Right now most of the
Long Distance dialing is done by operators, but research is hastening the day when
you will be able to dial directly to other telephones all over the nation.
Bell Telephone Laboratories
Improving telephone service for America provides careers for creative men in
scientific and technical fields.
Posted March 2, 2020