IBM 2260
Encyclopedia
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 transistor
s. Mainframe computer
s 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 end and a torsion 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 usually 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
bit
s 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 connected terminals.
Cathode ray tube
The cathode ray tube is a vacuum tube containing an electron gun and a fluorescent screen used to view images. It has a means to accelerate and deflect the electron beam onto the fluorescent screen to create the images. The image may represent electrical waveforms , pictures , radar targets and...
(CRT) video display terminal plus computer keyboard
Computer keyboard
In computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches...
was a 1964 predecessor to the more-powerful color text-and-graphics IBM 3270
IBM 3270
The IBM 3270 is a class of block oriented terminals made by IBM since 1972 normally used to communicate with IBM mainframes. As such, it was the successor to the IBM 2260 display terminal. Due to the text colour on the original models, these terminals are informally known as green screen terminals...
. The 2260 screen image was normally configured with 12 lines of 80 characters each, which corresponded to IBM punch card
Punch card
A punched card, punch card, IBM card, or Hollerith card is a piece of stiff paper that contains digital information represented by the presence or absence of holes in predefined positions...
format. The IBM 2260 and successor devices were transitional punch-card-to-CRT computer hardware that inspired many office of the future
Office of the future
The office of the future is a concept dating from the 1940s. It is also known as the "paperless office". After sixty years of unfulfilled prophecies the phrase "paperless office" has been discredited somewhat...
authors to write about the potential of the paperless office
Paperless office
A paperless office is a work environment in which the use of paper is eliminated or greatly reduced. This is done by converting documents and other papers into digital form. Proponents claim that "going paperless" can save money, boost productivity, save space, make documentation and information...
.
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
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
chips, the technology was based on discrete-component individual transistor
Transistor
A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...
s. Mainframe computer
Mainframe computer
Mainframes are powerful computers used primarily by corporate and governmental organizations for critical applications, bulk data processing such as census, industry and consumer statistics, enterprise resource planning, and financial transaction processing.The term originally referred to the...
s used magnetic core
Magnetic core
A magnetic core is a piece of magnetic material with a high permeability used to confine and guide magnetic fields in electrical, electromechanical and magnetic devices such as electromagnets, transformers, electric motors, inductors and magnetic assemblies. It is made of ferromagnetic metal such...
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 end and a torsion 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
Voice coil
A voice coil is the coil of wire attached to the apex of a loudspeaker cone. It provides the motive force to the cone by the reaction of a magnetic field to the current passing through it...
. A fraction of a second later, the other end of the mechanical wire would vibrate. The vibration was converted to raster scan
Raster scan
A raster scan, or raster scanning, is the rectangular pattern of image capture and reconstruction in television. By analogy, the term is used for raster graphics, the pattern of image storage and transmission used in most computer bitmap image systems...
lines and sent to the nearby CRT display. The IBM 2848 delay line was a continuous electromechanical feedback
Feedback
Feedback describes the situation when output from an event or phenomenon in the past will influence an occurrence or occurrences of the same Feedback describes the situation when output from (or information about the result of) an event or phenomenon in the past will influence an occurrence or...
loop.
Mainframe computer systems were usually 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
Digital
A digital system is a data technology that uses discrete values. By contrast, non-digital systems use a continuous range of values to represent information...
bit
Bit
A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...
s 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 connected terminals.