“DISPLAY” is a very important concept in the world of computing. It’s even a verb in the COBOL programming language. And it’s more than just a device in the world of computing hardware — it’s an entire journey. That journey has involved the emergence of the concept of interactively showing information versus just printing it for later review. It has involved electron guns emitting electron beams, phosphorescent screens, and large glass vacuum tubes (with no air inside).
Today, with LED (light-emitting diode), OLED (organic light-emitting diode, also known as organic electroluminescent diode), LCD (liquid crystal display), and plasma displays having created the thin, lightweight standard for displaying just about everything, even in projectors, it’s easy to forget that within the last century we’ve climbed from flickering lights and paper printouts and punched cards into a world where the only evidence of these steps on the journey are antiquated references that linger in the language.
Oddly, back on Dec. 20 — and for that matter, every Dec. 20 — there was a special designated day for the celebration of the displays that were standard for the first few decades of consumer-oriented computing: cathode-ray tubes (CRTs).
But perhaps this commemorative day can give us a moment to pause and consider the history of computing from the perspective of such appearances.
After all, in the earliest days of computing, real-time interactivity was not a standard expectation of a machine that was seen as a glorified complex calculator, whose calculations would be run in a batch job and the results printed out or punched onto cards.
For that matter, early CRTs weren’t simply seen as a way to provide an interactive display. Some were even used as a form of data storage, where the face of the tube contained bits of electromagnetic storage!
Movies such as “The Imitation Game” give us a picture of the earliest computing environments, where the computing device was configured to resolve a problem and would stop running when the task had been completed — no screen involved. The idea of real-time interaction with the computer was still nascent in the times depicted in the movie “Hidden Figures,” even though the concept of CRTs had emerged and was present in devices such as televisions. For that matter, in the movie “War Games,” while a terminal session with the computer was depicted as possible using a dial-in modem, the primary mode of interaction and display of the computer in question was still using individual lights.
Like so many other parts of recent history, the 1960’s were the real turning point for interactive displays, and while the space race played a significant part in this progress, so did the concept of time sharing, where multiple users would interact real-time with a computer, rather than just submitting punch card programs for later queued execution. While printer terminals were feasible for such real-time interactions, terminals with tubes and keyboards saved on paper costs and were much simpler to use and transport — if still a bit heavy to lift.
By the advent of the personal computing era in the 1980’s, CRTs were the standard display technology for everything from TVs to personal computers to terminals for larger systems, and even early “portable” (or perhaps more accurately “luggable”) computers had small embedded CRTs, or the ability to use RF modulators to send their display images to home TVs which, after all, were also CRT technology.
Today, it is rare to see one of these heavy glass tube display devices, even though they were pervasive until the arrival of lightweight, flat displays. One might suggest that the arrival of laptops with flat displays heralded the beginning of the end for them. And yet, fossilized references persist in our language, such as “tube” in “YouTube” and “video” which refers to an empty (“vide” in French) display tube.
As someone who never found it pleasant to lift a 27” TV with a cathode ray tube in it, I’m thankful that I can easily pick up a much larger flat screen, and that I don’t even need an RF modulator to get my laptop to send its screen image directly onto such a display. But I’m also thankful for the era of the empty display tube that gave us such an effective on-ramp to our current array of displays