The first transatlantic cable was laid out between 1854 and 1858 an...
Reservisor
*Terminal on the left and drum memory units on the ri...
The Hollerith machine was an electromechanical machine designed to ...
This is what a typical reservation center looked like in 1949. A bi...
Starting in the 1950s the number of air passengers would explode wo...
**Teleregister stock display**
Large screens displayed current d...
[Here](http://archive.computerhistory.org/resources/text/Teleregist...
**Baudot Code** is a character set predating ASCII that was invente...
The **Mark I** was a general purpose electromechanical computer dev...
[Here](https://d.lib.ncsu.edu/computer-simulation/videos/julian-rei...
The Reservisor Automated Airline
Reservation System: Combining
Communications and Computing
JON
EKLUND
Shortly after the beginnings of the computer in the mid-
1940s,
a machine
appeared that was the first in a long line of important commercial systems inte-
grating communications and processing: the Reservisor airline reservation
system built by the Teleregister Corporation.
A
few parts of the original have
been preserved at the Smithsonian Institution, and there are enough records
to understand both the basic issues in the airline industry that led to the devel-
opment of this remarkable device and how the machine helped solve some of
the problems of rapidly evolving air-transport technology. This article also dis-
cusses the place
of
the Reservisor in the larger view of the development of in-
formation technology.
odern information technology is historically founded
M
on two deep footings: communications and process-
ing. While both can be traced back beyond the historical
record, arguably the greatest change in each occurred when
their technologies became electrically driven.
As the first truly “modern” technology, communications
led the way into the age of the immediate with the Morse
telegraph in the late 1830s. Not long after came the popular
miracle of the Atlantic cable. which connected continents.
From the effort to carry multiple telegraph signals on
a
single wire (since erecting telegraph lines was fearfully ex-
pensive) came the telephone in the 1870s. The name “wire-
less” correctly suggests
a
desire to avoid that enormous
economic drawback
-
wires
-
which plagued both the
telegraph and telephone. Sending signals through the air (or
ether)
was
but one more miracle from
a
long line of unfore-
seen leaps into hard-to-believe futures for communications
technology in the nineteenth century. The leaps from wire-
less to radio to television are familiar to most of us. Thus
were spawned the “glamour industries” of most periods in
the nineteenth and twentieth centuries.
Curiously, electrically driven processing on
a
large scale
lagged communications by nearly
a
century, perhaps be-
cause the
modification
of information inherently requires
more steps and internal subsystems than
moving
it.
To
be
sure, the Hollerith machine and its card-based electrome-
chanical descendants were impressive and important, but
their impact on the social and commercial world was not on
the same scale
as
the telephone or even the telegraph.
Indeed, influences of that scale did not happen until the
advent of computers which, of course, have turned out to be
the quintessential information engines.*
~~___
*
In May
1990,
the National Museum
of
American History opened
the most extensive and complex technology exhibition in the
As we
also
know. there has been
a
clear trend to combine
processing and communications technologies in various
ways and to varying degrees.
For
example, digital processing
technology now plays
a
central role in television. Beyond
the obvious ever more elaborate graphics and animation
tricks lies the crucial infrastructure of digital switching. In
the last year
or
so,
the media have trumpeted ambitious
plans for “information highways” to transmit unimaginable
amounts of computer data. For even longer periods, news-
paper articles and other media sources have let the public in
on the trendy and even useful fun of computer bulletin
boards and commercial “on-line” services. Less well known
is the fact that, shortly after the beginnings of the computer
in the mid-1940s,
a
machine appeared that was the first in
a
long line of important commercial systems integrating com-
mercial communications and processing: the Reservisor air-
line reservation system built by the Teleregister Corpora-
tion. As far
as
we know,
all
that survives of the system is an
agent set. two racks, and
a
magnetic-drum memory, which
are now housed in the Smithsonian Institution.**
The background to the Reservisor
system: The reservations problem
Whether an airline flight was short or long, the problem
was in sending and receiving immediate and accurate infor-
mation. An oversold flight meant angry passengers. On the
other hand, an unoccupied seat suffered an immediate 100
percent markdown
as
the plane closed its doors.
Smithsonian‘s history: “The Information Age.” This introductory
material is from the original themes
of
the exhibition.
*:b
The agent‘s set is now on display in the exhibit “Beyond the
Limits“ in the National Air
and
Space Museum. This exhibit covers
the history
of
computers in aerospace technology.
.
~~ ~~ ~~
105H
hlh0144
$1
00
c
IO94
IEEE
62
IEEE
Annals
of
the
Hittory
of
Corripputing,
Vol.
16.
No.
1.
1994
Early methods of airline reservations were ingenious
make-do systems based
on
the systems used for slow-mov-
ing Pullman accommodations. The basic technology con-
sisted of telephone calls made by agents. Flights were han-
dled from the point
of
origin. This had a somewhat different
meaning in the immediate postwar period. The gains in the
range of airplanes developed during World War I1 would
take a few years to come into wide use in commercial
aviation. Limited ranges meant that longer flights were
broken up into “legs.” Each “leg” was treated as an origina-
tion. Longer flights meant that a ticket agent had to combine
legs by phoning a
series
of origination points.
Flight information was sent and received through a com-
plicated system of manual operations. The booking point
had a manual display board (often using chalk) which re-
corded the number of available seats
on
a particular flight.
Local agents were in sight range
of
the board: some even
used binoculars. Agents or travelers from other locations
seeking reservations by phone suffered from time lags in-
volved in getting, using, and modifying the data
on
availabil-
ity of flights. Advance sales or cancellations might be initi-
ated by letter, by telephone, or in person. But all ended up
as a written record at some point. sent to a central inventory
control unit. There was inevitably much guesswork about
selling or not selling seats, and many frustrations and diffi-
culties in communicating effectively with agents,
as
most
reservations information exchange was done by phone.
Overbooking was reportedly common.
If
anything, return
reservations were even more difficult
to
do.
A point-of-origin agent could see the board, of course,
but the official availability data was that held in the central
ticketing office. If there was a question about seat availabil-
ity, even the local agent had to call this office. As air travel
increased, it became clear that the system was
on
its way to
breakdown.’
Other ideas for automating airline
reservations
There are indications of one or two early conversations
and proposals to automate reservations in some way or
another. Ralph Damon, president of American Airlines,
was approached by Sperry in 1945 with an offer to design a
system. Damon was obviously not convinced, since the air-
line selected Teleregister later the same year.
In
1947, well after the Teleregister effort was under way.
Engineering Research Associates of St. Paul, Minnesota
(later bought out by Sperry) wrote a “Proposal for Auto-
matic Space Reservations System,” which featured the use
of
an
electric typewriter as the input and output device. In
the same year, the
Sr.
Paul Dispatch
carried an announce-
ment that Northwest Airlines had access to some kind of
device that could give a yes or
no
on
requests for airplane
seats. There is
no
evidence that either
of
these two systems
was ever built.
American Airlines takes up the challenge
Just after the war, with a clear vision of the potential
problem, the head of American Airlines’ Systems and Meth-
ods Division, Charles Ammann, researched the various
existing methods for handling seat inventories.
He
con-
cluded that all were as limited as those of his own com-
pany. Carefully analyzing the various aspects
of
American’s traditional “request and reply” and “sell and
There was inevitably much guesswork
about selling seats and frustration in
communicating with agents, as most
reservations information exchange
was done by phone.
report” systems, Ammann outlined solutions to existing
bottlenecks:
1.
A new system should present the flight information
necessary for the customer’s decision immediately
and clearly.
2.
The new system should keep track of ticket sales and
cancellations as they occur and keep up an accurate
running inventory.
3.
The agent’s machinery in the new system should re-
tain a record of the most recent transaction until
consciously cleared or until another transaction re-
placed the previous one.
4. The system should automatically let all agents and
sellers know immediately when a flight was sold out.
5.
The system should perform these tasks economically
and be capable of expansion.
Using his training as a radio engineer, Ammann built a
limited working model of an electronic inventory-control
system. The model assumed three flight legs in three days
with three agents connected to the central office. Relays
served as storage, and availability was indicated by lights.
Simple push-button switches set up availability queries.’
Ammann brought this model to the president of Ameri-
can Airlines and sold him on the idea
of
a flight reservation
system? After considering various possibilities for a com-
mercial developer for the project, American Airlines nego-
tiated with the Teleregister Corporation in 1945 for its
construction.
The Teleregister Corporation
Teleregister was founded in the 1920s to handle the
display of stock market transactions using automated dis-
play boards instead of handwritten entries
on
chalkboards.
The founder was Frenchman Philip Dreyfus, who had been
in the French signal corps. Dreyfus was familiar with French
signal techniques such as Baudot codes. which were more
sophisticated than the Morse system. He became a pioneer
in the teletypewriter and teleprinter business. It is said that
he got the idea of displays during the growth of the stock
business in the 1920s. Large Teleregister boards became
fixtures at many brokerage offices, and Teleregister became
the leader in this technology.
IEEE
Annals
of
the
History
of
Computing,
Vol. 16,
No.
1,
1994
63
Reservisor Airline Reservation System
Immediately following the war period. the firm was
lo-
cated in Stamford. Connecticut.h
The Reservisor pilot project
The Teleregister information boards used in brokers’
offices for stocks were not very different in intent from the
manual boards used by the airlines. This may have been why
Teleregister was selected for the contract to do a pilot
project for the American Airlines office in Boston. The
system was installed
on
February 2,1946.
The Boston board was but a little more sophisticated
than Ammann’s electronic model of the desired system. It
was local, had no remote capabilities, and was designed to
test the
processing
phase of the operation withouta commu-
nications tie-in. Perhaps Teleregister felt confident about
the communications, since most of the boards they installed
in brokerage houses were sent information over the tele-
typewriter lines.
In
any event, there was
no
overall count
of
the immediate number of seats available, only whether (or
not) the immediate request could be
Even though they were in the same location as the central
information system, the agents used the machines rather
than voice or eye communication. They queried the system
by pressing contact button switches and received light sig-
nals to indicate availability, just as they would in a remote
location. Though there really was little gain in this test
situation over the sight method, Teleregister engineers and
the airline learned much about the potential of the system.
There were more tangible benefits. It was faster to record
availability data using plugboards than writing on a chalk-
board. The working rooms could be smaller, too. since the
large visual display could be eliminated with the use of the
agent set.
Each agent was now a relatively independent unit. Since
the information reached the agent directly. sales could be
closed immediately without the lag necessary to contact the
central board or office by telephone and get the information.
Perhaps the most interesting lesson was the surprising
reaction
of
the public to the device. Agents discovered that
the reactions of the customers to unavailable flights were
less
negative. Customers felt that the machine was unbiased
and neutral, and would give them accurate information. By
contrast, the public sometimes suspected agents of holding
out
on
them or of favoritism.‘
The Boston office continued in operation through the
late 1950s until it was made part of the SABER” system
in
the early 1960s. The somewhat peculiar triangular agent
sets, as well as other parts of the system, were upgraded over
the course of the lifetime of the Boston station.
The development
of
the “Magnetronic”
Reservisor
There are tantalizing indications of a transfer
of
knowl-
edge in reservations technology and procedures from the
*
American Airline’s successor
to
Reservisor
was
originally
named SABER. an acronym
for
Semi-Automatic Business Envi-
ronment Rescarch. The name was changed
to
SABRE
in
1959
for
marketing reasons.
~ ~ ~ ~~~ ~~ ~~~ ~~ ~
railroads
to
the airlines. The railroads had reservation sys-
tems for a long time, of course, and early in the development,
Teleregister hired a number of railroad people who in fact
stayed with the Reservisor division over its lifetime. One
witness claims to have seen the same route maps used to
schedule the movement of railroad cars being used for
planes. A lot of procedures had, according to coworkers
formerly from railroads. been moved directly from railroads
to airlines, including the communications
Another important resource for the computer side was
Howard Aiken, who had built the Mark
I
relay calculator at
Harvard University and who was a consultant to Teleregis-
ter. It was said that much of the logic of the Reservisor
system came from Aiken. Aiken was reportedly seen around
the Connecticut headquarters for meetings.6
Most “teams” that develop
a
piece of technology experi-
ence turnover during the period
of
the project, and always
seem to the members and leaders to be at less than full
strength. The group who developed the Reservisor was
no
exception, but work was started in April 1949
on
the La-
Guardia location in spite of shortfalls. The first working
version of the Reservisor, known rather pompously as the
“Magnetronic Reservisor” after its magnetic drums, was
working reasonably well by the spring of 1952. It was un-
veiled and put into full service in June of that year. The next
generation came
in
1956 with enlargements
in
the amount
of memory. which allowed more flights to be handled. It also
handled the network of agent sets better and could reserve
more than 10 days ahead?,’”,”
The American Airlines system worked
so
well that even-
tually there were Teleregister systems at TWA, United,
Braniff, National, Northeast, Pan American, and Western.
To the disgust of the Reservisor management, Eastern even-
tually went with Univac.
The technology
of
Reservisor
The system was binary, which was in keeping with the
rather simple yesino nature of the information
on
availabil-
ity. For the time, the design requirements were impressive:
1.
2.
3.
4.
5.
6.
Storage capacity for
1,000
flights or flight stops (par-
tial flights).
Storage capacity for 10 separate dates for
each
flight
stop (10,000 units of “flight memory”).
Sufficient capacity in each storage record for an inven-
tory count of at least 100 seats.
Preservation of stored information in the event of a
power failure.
“Sufficient checks” to be able
to
detect incorrect input
signals, malfunctioning of electronic circuits, and in-
correct inventory quantities.
Random access to the memory.’’
The central computer was to be installed at LaGuardia
in an area of 1,000 square feet. It was designed as a mix of
tubes and relays, though the version built around 1957
ended up with some 4,500 tubes and 3,000 diode~.’~
More interesting was the fact that the machine was
built in a “fail-safe” configuration. As the block diagram
64
IEEEAnnals
of
the
History
of
Conzputmg.
Vol.
16,
No.
1,
1994
T-
(Figure
1)
of the Reservisor clearly
shows, it was actually two ma-
chines, each built around its own
magnetic-drum memory. which si-
multaneously worked
on
the same
input data. They compared signals
at every stage and would print error
messages for service personnel if
there were discrepancies.
Most
of
the time, problems could be located
quickly and solved within a few
minutes. The duty cycle of the ma-
chine was 22 hours, with two hours
of scheduled maintenance
each
Saturday nights there was a
longer downtime for more elabo-
rate scheduled checks. Unsched-
uled downtime was reported
as
less
than a tenth of one percent. Tube
reliability was over five times better
than predicted. During the entire
first year of operation. it was neces-
sary
to
change only 129 tubes, or
about
10
per month. Further work
on maintenance schedules and tube
selection got the tube life to the
point that the machine went two to
four months without tube failure.
day.'
COMPUTING COMPARATOR
EQUIPMENT
MASTER UNIT
a
COMPUTING
EQUIPMENT
I
I
~
I
SEEKER EQUIPMENT
I
I
-I
ALARM
MAGNET
IC
STORAGE
I
Figure
1.
Block
diagram
of
the Reservisor (Charles
E.
Smith Museum, Dallas).
The Smithsonian has the drum from the first Reservisor.
Markings are engraved on the drum. There were 20 to the
inch, meaning that the bit density
on
the drum tracks was
20
to the inch. The drum provided for
1,024
memory locations
repeated in
10
circumferential sections. Each date section
provided
7
bits, giving a count of
128
per memory "bin."
Magnetic storage on the drum protected the inventory data
from power failure.
Actually. there were two drums locked together. Tech-
nicians could disassemble them and replace one with the
other if the first failed. The second drum functioned as
a
backup. (In the first four years of operation, however, it was
necessary only
once
to take one of the two halves of the
machine
off
line.) During the input storage operation, the
system wrote to both drums, but read from only one. There
was reserve capacity, since doubling the packing factor from
20 to
40
to the inch would allow 2,048 "bins" on the periph-
ery. Figure 2 shows a section
of
the Reservisor magnetic-
drum memory.
Design was very conservative, with an emphasis on reli-
ability rather than speed. The access time was given as
50
ms." The goal was to have a device that was more reliable
than any other type of data-handling machine or system
of
people. Wherever possible (if there was enough time), twin
contact relays were used instead of tubes because of their
reliability.
All
components were mounted
on
plug-in assem-
blies for easy servicing and minimum downtime. All trans-
actions were introduced into
both
halves and compared for
similarity at four key steps.
lf
there was
a
discrepancy, error
signals were generated.'*
The instructions for the machine were hardwired. There
was
no
intent to build any kind
of
general-purpose computer.
The
public's
experience with this
technology
If the traveler came
to
the agent's station. she or he would
one of a number of coded destination plates (see
Figure
3)
and
.
an input and output device called an agent set
(Figure 4) that looked rather like a slightly over-
sized version of a calculating machine of the period.
see the operator involved with two pieces of equipment:
Two additional parts of the system were hidden:
the telephone lines and
the computer (Figure
S),
located at LaGuardia air-
port.
The coded plate could fit into the agent set slot
in
four
ways (front top or bottom, and back top or bottom) and thus
hold up to four groups
of
flights. Each group (orientation of
the plate) had eight columns of information and thus held
up to eight flights over some part of the day (e.g..
6
a.m. to
5
p.m.,
3
p.m.
to
9p.m., and
so
on)."
A
would-be traveler would enter (or telephone) and ask
the sales agent at a ticket office for a particular flight or a
general flight time up to
10
days in advance. The agent
selected
a
plate that had the requested destination and time
of day, then placed the plate in its slot in the agent set. The
agent then punched in the desired date (up to
10
days away)
IEEE
Annals
of
the History
of
Computing,
Vol. 16,
No.
1, 1994
65
I
Reservisor Airline Reservation System
Figure
2.
A
section
of
the magnetic-drum memory
of
the Reservisor (Charles
E.
Smith
Museum, Dallas).
and the number of seats (up to four). Finally, the agent
pulled the right-hand switch (“AVAIL”) to start the check
for
availability.”
The next steps were done by the machine. It made the
connection via the leased teletypewriter line to the central
computer at LaGuardia. The computer accepted the inputs
of
destination, date, and number
of
seats. Then it searched
for the number of unsold seats on all of the flights (as many
as eight) listed
on
the plate. All flights listed on the plate that
had available the requested number of seats got a coded
signal back from the computer. On the agent’s set, the coded
signal was identified and sent to
a
light below the appropri-
ate column of the destination plate. Travelers who were
familiar with the system might wait anxiously for the light to
come on under their preferred flight or time of day,
or
for
several lights
(if
they liked to have choices). or for any lights
at
aIL6
Thus, within
a
few seconds. the
agent could tell the traveler which
flights were available for the num-
ber of seats wanted. When the trav-
eler made up his or her mind and
chose
a
flight, the agent pushed the
switch that accompanied the avail-
ability light for that particular
scheduled flight, and then pulled
the “sell” switch on the lower left of
the keyboard area. The agent’s set
then sent a signal to the central
computer requesting another check
of
the availability of the desired
seats. If they were still available,
that number was subtracted from
the day‘s seat inventory. The com-
puter then sent a confirmation sig-
nal back to the agent’s set, and the
upper green light
on
the panel
lighted.
If
the inventory was depleted
while the traveler was deciding and
the seats were suddenly
no
longer
available, the lower “reject” light
turned
on
and seats were not sub-
tracted
from
the inventory.
The technological
lessons
of
Reservisor
There
was
little question about
it. As one observer of the scene
summarized Reservisor’s perfor-
mance in
1956:
It [the Reservisor] shows that in-
formation can be processed by a
central computer, at the time the
transactions occur [real time].
with negligible delay. and with
inputs scattered over
a
larae ee-
ographical area. It shows that an electronic system can
provide important by-products, the value of which is
hard
to
estimate
...
It shows that customer service can
be improved, by answering inquiries more rapidly and
by reducing the chance for overselling a flight due to
human bookkeeping errors.
And
it
shows
that a com-
plex electronic system can provide reliable operation to a
degree generally not attainable
by
manual or punched
card
methods
[italics mine].”
We take all of these for granted now,
of
course. but at that
time these characteristics were not all certain and taken for
granted.
To
many, they were startling.
But technology is more than an assemblage
of
devices,
and nowhere is that illustrated better than in the human
limitations
in
the use of Reservisor. When Julian Reitman was
hired in 1955, part
of
his
job
was to study the patterns of usage
66
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Annals
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the History
of
Computing.
Vol.
16,
No.
1.1994
I
and practice, and the traffic that
resulted. He discovered that Amer-
ican Airlines seldom, if ever, used
the Reservisor system in the way it
was designed to be used.
The system was designed to auto-
matically decrement the total num-
ber
of
seats available by the number
entered by the agent
as
sold. What
Reitman discovered was actually
happening was that the number was
not decremented until the sale had
been registered manually by
a
clerk
at the machine’s installation, and a
slip had come down to the operator
on
a conveyer belt. Somehow when
the crunch came the people
on
the
operating end couldn’t quite bring
themselves to trust the machine, and
kept a human
in
the loop. After the
handwritten slip came down to the
operator, he would decrement the
number manually.”
Not
all
of the lessons were
so
straightforward. Between 1956 and
1959, Reitman did studies compar-
ing standard communications theo-
ries with the actual performance of
the Magnetronic Reservisor sys-
tem. The system was anomalous by
comparison with standard tele-
phone networks.
Of
the agent sets
tied
to
the main office at LaGuardia
(a number which varied between
50
and
XO),
some
75
percent were at
the large reservations amphithe-
ater
on
42nd street. The rest of the
information came in
on
communi-
cation phone and teletypewriter
lines from remote locations. These
lines worked at the incredibly slow
pace of
50
baud (about
5
percent of
Figure
3.
Destination plate for a Reservisor agent set (Charles
E.
Smith Museum, Dallas).
the speed of the common modem of the late
1980s).
In
a real
sense, the engineers did
not
understand how the machine
actually functioned in practice because the standard com-
munications concepts did not apply
to
the Reservisor Sys-
tem.6
Reitman and his colleagues (notably a mathematician,
Jerry Harrison, who worked with Reitman) tried
to
under-
stand how the machine worked from a theoretical stand-
point. They used “queuing theory,” which is a part of clas-
sical communications theory. Harrison and Reitman
investigated the question of whether these theories really
applied to traffic on airline reservation systems using com-
puter terminals. This was
a
real-time system, with properties
like communications response times and peak traffic service
characteristics that people at Bell labs were writing and
talking about. The Bell theoreticians produced complex and
often elegant mathematical equations to describe such sys-
tems, but Reitman and Harrison found that Bell’s equations
did
not
fit realities
of
the system,
as
the Teleregister engi-
neers were measuring them in periods of peak traffic.
Specifically, Reitman noticed that transactions were not
autonomous. For example, someone during a peak traffic
period would call in from San Francisco for a flight for, say,
Monday morning. If the flight was not available, there might
well be
an
immediately repeated call for Tuesday morning.
If that was full, for Monday afternoon or Wednesday morn-
ing, and
so
on.
Thus there could
be
five
communication
transactions to accomplish
one
reservation.
On
this basis,
communications theory wasn’t adequate, for it expected
communication to be an independent event. In Reservisor
traffic, however, there was a high probability for two or
more linked events
-
even as many as
Somewhat mischievously, the technical staff wondered if
there was a way that they could “jam up the machine”
as a
IEEE
Annals
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1,1994 67
Reservisor Airline Reservation System
Figure
4.
A
post-1956
Reservisor agent set (National
Mu-
seum
of
American
History).
means to measure the actual peak system capacity. Reitman
discovered, to his surprise. that he could freeze the entire
system by suddenly throwing in the transactions of just three
keysets. Of course, this depended
on
which keysets were
selected. It turned out that some had higher priority than
others in queries for service by the system. If your keyset
was connected to the central node of the switching system,
it had permanent priority and you could ensure that
nobody
else got any service. (In practical terms. that meant
no
response when another agent pushed the button on a set that
was supposed to query the system for information.)
There was
no
separate, definitive,
clear
indicator that the
system was locked or jammed. Part of the reason for not
having a specific "jammed" signal was that Teleregister did
not want to give the agent a clear indication that the system
was not working. The company was afraid to have any mode
of operation that was less than optimistic. By contrast, later
systems, when jammed or experiencing some other failure,
always sent the agent a message to the effect that he or she
had made a mistake and should reenter. The new philosophy
was that the agent
had
to have faith in the computer.'
Once Reitman had gathered and analyzed the informa-
tion, he knew that the design concept for the entire system
was faulty. The peak passenger traffic periods during the
week (Monday morning, Friday afternoon) were under-
stood and recognized. But the seasonal variations were
enormous,
so
the major peaks were much, much larger than
the averages. He and others started thinking about how to
better interconnect the agent sets to the system for greater
efficiency and thus flexibility. From this came Teleregister's
new, "unified" system. It was for this system that the agent
set shown in the photograph was made. The new set was
initially designed for TWA.
Reitman and other engineering staff summarized their stud-
ies in a series of publications in 1959. These seem to be aimed
at American Airlines in the hope
of
competing with IBM for
the new system. By that time, however, it was too late. IBM
had been involved with the successor project since 1953.6
Limitations of the Reservisor system
Much as the public might marvel at the Reservisor in
action, the airlines wanted more. Lists
of
passenger names,
telephone numbers and addresses at which passengers could
be contacted, and other information could not be taken,
stored, and manipulated. Nor could Reservisor do the large-
scale statistics of traffic on various flights or even the basic
arithmetic of gross total receipts at each sales location.
Though the technological potential was there, problems
between ATT and Teleregister initially prevented the vari-
ous
systems for each airline from talking to each
As early as 1953, convinced of the usefulness of auto-
mated systems by only a year or
so
of experience with the
Magnetronic Reservisor, American Airlines executives
were thinking about the next step. The often repeated story
about the chance meeting between C.R. Smith, president of
American Airlines, and
R.
Blair Smith, senior IBM sales-
man, on a transcontinental flight, has an air of inevitability
about it. The long conversation led to the creation of task
groups at both IBM and American Airlines to develop
methods for extending the capabilities
of
reservation sys-
tems beyond the basics of Reservisor!.'4 The five-year joint
study project led to a contract in 1958 for the creation of the
SABER (Semi-Automatic Business Environment Re-
search) system."
eservisor was the first commercial system to combine
R
electronic processing and electronic communications.
It demonstrated that the combination was not only feasible
but that it could be reliable in the extreme. For easy adap-
tation into society. a technology must be seen as enduring
and robust,
or
to have the potential for these important
attributes.
Reservisor was one of the first
inventory
systems to be
controlled by an electronic computer. Because it ran
so
long
and
so
reliably (the equipment operated
22
hours a day,
seven days a week, with a two-hour daily maintenance
period), it provided a testbed and standard for large-scale
heavy-duty information-technology applications. Reser-
visor provided data and a testbed for mathematical theories
of scheduling databases (for example. queuing theory). Its
reliability should be emphasized, for this was an electronic
system not far removed in time from the ENIAC, which had
68
IEEE
Annals
of
the
t€i\torr
of
Computing,
Vol
16,
No
1.
1994
T-
__.
-
-~
proved to be sufficiently reliable
but had down and repair times that
were not at all negligible. Reser-
visor demonstrated not only that
information could be reliably pro-
cessed by
a
central computer, but
also that it could be processed at the
time the transaction occurred or
with negligible delay, and that the
system could process information
with input stations scattered over a
wide geographical area.
The Reservisor is still remem-
bered with awe and some affection
by people in the industry. Surpris-
ingly, it has received rather little
notice in the historical literature,
despite the fact that it was clearly an
important precursor to the large
IBM systems which succeeded it.
In
the end, as one might expect,
Teleregister was no match for IBM.
and once
it
lost the American Air-
lines account
to
IBMs
SABER sys-
Figure
5.
The Reservisor installation (Charles
E.
Smith Museum, Dallas).
tem it gradually withered until it was bought out in the 1960s
by TRW, and disappeared into the conglomerate maw.
W
References
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
R.J. Serling,
Eagle: The Story ofAmerican Airlines,
St. Martin‘s
Press, New York, 1985.
R.F. Burkhardt. “The SABRE System: A Presentation.” Oct.
1,1964.
A.E. Keller, “American Airlines Automates Reservations for the
Jet Age,”
Management and Business Automation.
Jan. 1959.
R.F. Meyer, “American Airlines SABRE (A),” Case EA-C
758, Harvard Business School, Boston. 1967.
C.E. Ammann, “Airline Automation: A Major Step,”
Comput-
ers and Automation,
Vol.
6, No. 8. Aug. 1957.
Transcript
of
Julian Reitman Aural History Interview
of
Oct.
American Airlines, “America Long
a
Leader in Reservation
Systems,” Press Release, n.d., ca. 1959.
American Airlines, “Meet the Televisor,”
Flagship
World,
Vol.
2,
No.
2,1946,
p.
14.
Railway Age.
Vol.
133,
No.
3, July 21. 1952.
pp.
46-47.
Tele-tech,
Vol.
11,
No.
10.
Oct.
1952,
pp.
108-109.
R.G.
Canning.
Electronic Data Processing for Business and
Industry,
Wiley, New
York,
1956.
pp. 8-12.
C.G. Abbott. “The Magnetronic Reservisor.
A
Reservation
Inventory Control System” (originally presented at the Sixth
Southeastern Conference, Inst. of Radio Engineers, Feb.
5,
1954), printed and distributed by Teleregister Corp.. pp. 2.4-6,
10-14,17-18.
M.H. Weik,
A
Survey
of
Domestic Electronic Digital
Com-
puting.
Ballistic Research Laboratories, Aberdeen, Md.,
28,1987,
pp.
2-8,10-11. 15-19,22-24,27-31.
14.
1s.
1955.
p.
101.
Updated
in
second cdition.
1957.
pp. 224-230, and
third edition.
1961,
pp. 876-877.
C.J. Bashe et al.,
IBM’s Early Computers,
MIT Press, Cam-
bridge. Mass., 1986.
D.
Copeland. R.O. Mason. and J.L. McKenney. “SABRE: The
Development of Information-Based Competence. Part One.
1950-
1970,” to be published
in
IEEEAnnals
of
the Hisrory
of
Computing.
Jon Eklund
is a curator in the Division
of Computers, Information and Society
and also a curator in the Division of
Physical Sciences at the National Mu-
seum of American History
of
the
Smithsonian Institution. Over the past
few years, he has been researching the
history of various machines in the
Smithsonian’s computer collections and elsewhere, which
are representative of early computer applications.
Eklund has taught at Wesleyan University. Middletown,
Conn.: the University of Maryland, College Park; the
SUNY
program in Museology and Conservation
of
Art and Arti-
facts at Cooperstown, N.Y.: and the University of Maryland.
Baltimore County. He earned a
BS
in biophysics at Yale
University in 1958, an MA in physics from Wesleyan Uni-
versity in 1966, and a PhD in the history of science and
medicine from Yale University in 1971. He is a member
of
the History of Science Society. the Society for the History
of
Technology, and Sigma Xi. He serves
on
the board of
directors
of
the Computer Museum in Boston and the board
of
the National Plastics Center and Museum
of
Leominster.
Mass.
Eklund can be reached at the National Museum
of
American History, Smithsonian Institution. Washington,
DC 20560.
IEEE
Annals
of
the
Hirtory
of
Computing,
Vol.
16.
No.
1,
1994 69
**Baudot Code** is a character set predating ASCII that was invented by Émile Baudot. Each character is represented by 5 bits (see picture below). The symbol rate measurement is known as *baud* in honor of Émile Baudot.
[Here](https://d.lib.ncsu.edu/computer-simulation/videos/julian-reitman-interviewed-by-robert-g-sargent-reitman/) is a great interview with Julian Reitman where among other things he talks about his time at Teleregister, his problems dealing with peak traffic and trying to use Monte-Carlo simulations to try to solve the problem.
[Here](http://archive.computerhistory.org/resources/text/Teleregister/Teleregister.SpecialPurposeSystems.1956.102646324.pdf) is an old Teleregister catalog where you can see all of the special purpose computing systems their were manufacturing at the time.
The **Mark I** was a general purpose electromechanical computer developed in the early 1940s by Howard Aiken, an American Physicist.
Unlike the Reservisor (whose instructions were hardcoded), the Mark I was actually a general purpose computer. One of the first programs to run on the Mark 1 was written by John Von Neumann, who at the time was involved in the Manhattan Project and intended to determine whether implosion was a viable choice to detonate the atomic bomb.
*Mark I*
This is what a typical reservation center looked like in 1949. A big board, with workers taking calls from agents querying about flight availability.
Starting in the 1950s the number of air passengers would explode worldwide. Here is a graph depicting that growth:
**Teleregister stock display**
Large screens displayed current data on stock prices. Hundreds of boards on different trading floors were connected to the same central transmitting room.
Reservisor
*Terminal on the left and drum memory units on the right.*
The Hollerith machine was an electromechanical machine designed to help process and summarize information stored in punching cards. It was initially developed by Herman Hollerith to help with the 1890 U.S. census. Herman Hollerith was inspired by train conductors punching holes in railway tickets to record traveler details such as gender and age.
The company Hollerith founded, the Tabulating Machine Company, would eventually (via a merger) become be renamed IBM.
The first transatlantic cable was laid out between 1854 and 1858 and connected western Ireland to Newfoundland, Canada.
The first official telegram to be sent was a letter of congratulations between Queen Victoria and the president of the United States, James Buchanan on August 16th, 1858. It took about 2 minutes to transmit just one character. The signal quality rapidly declined in the following weeks and just on month later the cable was destroyed when Wildman Whitehouse applied excessive voltage while trying to achieve a faster operation.
*section of the cable*