The Tektronix 401x series
was a family of text and graphics computer terminals based on the company’s storage tube technology. The 4000 series were less expensive (under $10 000) than earlier graphics terminals, such as the IBM 2250 because no additional electronics were needed to maintain the display on the screen (beyond providing proper voltages to it). They 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. The new graphics workstations used raster displays and dedicated screen buffers that became more affordable as solid state memory chips became cheaper.
Computer Display Review, March 1970, Keydata Corp., p. V.1982
“The Tektronix 4010 Graphics Terminal”. 090527 columbia.edu
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 due to the high cost-per-bit of contemporary memory devices.
Tektronix solved this problem by developing the Direct View Bistable Storage Tube (DVBST) CRT, which 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.
As the terminal stored the image electronically, all that needed to be sent to it was update instructions. This could easily be handled by a conventional serial link, allowing the terminal to be located anywhere.
For graphics input, the terminal used a pair of thumb wheels on the keyboard to control the position of a cursor. The cursor was displayed using a lower intensity of the electron beam that was insufficient to store the cursor’s image. Instead, the cursor was dynamically refreshed by the electronics of the terminal.