IBM 2260

The text-only 960-character monochrome IBM 2260 cathode ray tube (CRT) video display terminal plus computer keyboard was a 1964 predecessor to the more-powerful color text-and-graphics IBM 3270. The 2260 screen image was normally configured with 12 lines of 80 characters each, which corresponded to IBM punch card format. The IBM 2260 and successor devices were transitional punch-card-to-CRT computer hardware that inspired many office of the future authors to write about the potential of the paperless office.

Up to sixteen 2260 terminals were clustered around an expensive IBM 2848 central controller that stored the digital image of screens of information in a "delay line." Before the introduction of integrated circuit chips, the technology was based on discrete-component individual transistors. Mainframe computers used magnetic core memory, which was too expensive for use in video display terminals. The delay line was an unusual mechanical (not electrical) spiral wire with an electromagnet on one ened and a tortion rotation detector on the other (which was conceptually similar to an old-fashion phonograph needle pickup). The central controller system vibrated the electromagnet like an audio-speaker voice coil. A fraction of a second later, the other end of the mechanical wire would vibrate. The vibration was converted to raster scan lines and sent to the nearby CRT display. The IBM 2848 delay line was a continuous electromechanical feedback loop.

Mainframe computer systems were ususally mounted on raised floors with cables underneath. One humorous effect of the 2848 delay line was that if a heavy person walked next to the controller, or if it was mounted next to a vibration source (like an elevator), digital bits of screen images would be lost on all of the video displays, which would then be repeated continuously through the feedback loop, until a new video display was transmitted to all of the conneceted terminals.

External links

• History of the IBM 2260 Display Station