- published: 17 May 2015
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The Tektronix 401x series was a family of text and graphics computer terminals based on the company's storage tube technology. Beyond providing proper voltages to the storage tube, no additional electronics were needed to maintain the display on the screen, so the 4000 series were less expensive (under $10 000) than earlier graphics terminals, such as the IBM 2250, and were widely used in the CAD market in the 1970s and early 1980s. There were several members of the family introduced through the 1970s, the best known being the 4010 and 4014. They remained popular until the introduction of inexpensive graphics workstations in the 1980s, which used raster displays and dedicated screen buffers that became more affordable as solid state memory chips became cheaper.
Prior to the 4010, released in 1972, most computer graphics was done with vector graphics displays that continuously repainted the image under computer control. This required a very high bandwidth connection to the computer, which generally meant the display could be no more than a dozen or so meters from the computer. The modern approach of having a local memory in the display that stores a value for each pixel would have been prohibitively expensive in the 1970s. Tektronix solved this problem by developing the Direct View Bistable Storage Tube (DVBST) CRT, which allowed the use of a slower serial data connection combined with a vector graphics generator that only needed to write the vectors (the graphic data) to the CRT once. Having had data written, the CRT itself remembered the data. New content could be added to the displayed image, but individual portions of the image could not be erased. Instead, the entire displayed image had to be erased, a process that caused the entire screen to flash bright green. The revised image would then be repainted from scratch.