1950 to 1959: Starting the Ascent of Digital Computers and Software - The Technical and Social History of Software Engineering - page 83

also included in the SAGE architecture, which could direct the firing of Nike air-
defense missiles as well as long-range strategic missiles aimed at retaliation in the
event of an attack.
Prior to SAGE, there were numerous radar installations, but they were in-
dependently operated. There was also a Ground Observation Corps with 8,000
lookout stations that were only connected by telephones to command centers. A
hurricane or a Nor'easter could shut down air defenses because it would interfere
with radar tracks, block visual sighting of anything above the clouds, and blow
down many telephone lines, thus cutting off vital defense communication.
Development of the SAGE air-defense system started circa 1950 at the begin-
ning of the decade, and the system became operational in 1958. There were a num-
ber of upgrades to SAGE computers and other hardware devices over the years
until replacement in 1983.
The original SAGE software package consisted of about 500,000 statements in
a basic assembly language, which is equivalent to about 15,625 function points.
While this was the largest software application at that time, there are now applica-
tions that are more than 10 times larger.
The SAGE system operated until 1983, when it was replaced by newer systems
using a combination of airborne radar and ground command posts. The total cost
of SAGE was not released, but it is estimated to approach $12 billion during the
1960s (or perhaps $100 billion in today's dollars).
The IBM AN/FSQ-7 SAGE computer was physically the largest computer ever
built, and that claim is probably true even today because, soon after, transistorized
integrated circuits would shrink computers to a small fraction of the size of va-
cuum tube computers. The IBM SAGE computer had about 60,000 vacuum tubes
and weighed about 250 tons.
The SAGE technology, developed by IBM in Kingston, New York, would play
a major part in civilian air-traffic control systems in future years and would also
be part of the SABRE airline reservation system (or Semi-Automatic Business Re-
search Environment ). In fact, some of the IBM personnel from SAGE moved into
SABRE development later in the decade.
SAGE and SABRE catapulted computers and software from laboratory curios-
ities used for a narrow band of scientific and military calculations into major tools
that would revolutionize both national defense and business operations. SAGE and
later SABRE also catapulted IBM to the top of computer companies, a place where
it still resides today.