by Conrad Weisert, December 26, 2016
ŠInformation Disciplines, Inc.
NOTE: This document may be circulated or quoted from freely,
as long as the copyright credit is included.
Sixty years ago large-scale computers were still a novelty, and most citizens had never seen one. Organizations that used a computer for sensitive (classified or secret) applications would hide their machine in a secure room accessible only to authorized personnel. But many other organizations were proud to show off their giant electronic brain where it could be admired by visitors or even by the general public. Many computer rooms featured large picture windows through which one could observe the flashing lights, scurrying operators, and spinning tapes.
Some of those configurations were impressive indeed, and would still be so in today's world of super-miniaturized equipment. Those in public places would often draw crowds of curious spectators.
Before long nervous management noted that an impressive public display was also an extremely vulnerable target for vandals or saboteurs. A stick of dynamite or even a well-aimed rock could disable some of an organization's vital functions. And the truly paranoid suspected that spies could infer vital secrets from the patterns of flashing lights!
So the era of proud machine-room display didn't last very long. Highly visible computer rooms are a thing of the past not only in order to avoid unnecessary vulnerability, but also because today's smaller equipment offers much less to see. Very few up-to-date computer applications spin reels of tape, and computer consoles contain far fewer lights and dials than the old machines had.
The ultimate in caution may have been practiced by a few organizations working on super-sentitive applications. One didn't actually have to see the target machine in order to spy on it, some assumed. A running mainframe computer emits radiation, and such radiation exhibits characteristic patterns specific to the software being run. It might even be possible to infer the values of data items being manipulated.
We on the outside don't know whether those fears were valid or not or whether anyone ever succeeded in reconstructing both software and data from detected radiation. The fears, however, may have been responsible for some computers being installed inside specially-constructed radiation-blocking rooms. Naturally those stand-alone computers had to be dedicated to a single application at a time, forgoing the economies of multiprogramming and job queueing, and must never be connected to any network or external communication device.
Today, of course, dedicating a computer configuration to a single job is less extravagant, and we assume that organizations are taking appropriate precautions to assure the maintenance of necessary secrecy.
Last modified December 26, 2016
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