Browse Prior Art Database

Dot Matrix Display Compositor

IP.com Disclosure Number: IPCOM000093290D
Original Publication Date: 1967-Aug-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 5 page(s) / 60K

Publishing Venue

IBM

Related People

Propster, CH: AUTHOR [+3]

Abstract

This display composition system is applicable to most dot matrix displays. It is particularly well-suited for high-speed display composition in computer-assisted instructional CAI systems employing cathode ray tube CRT displays. The material desired to be displayed is obtained under program control from the input device in which it is deposited. An electronic compositor EC is arranged for translating a stream of computer-coded characters and symbols into a sequence of the appropriate displayable dot patterns. These patterns are obtained from glossaries of display characters placed directly in core storage of a central processing unit CPU. As they are translated, the dot patterns are temporarily stored, a line at a time, in a portion of CPU storage.

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Dot Matrix Display Compositor

This display composition system is applicable to most dot matrix displays. It is particularly well-suited for high-speed display composition in computer- assisted instructional CAI systems employing cathode ray tube CRT displays. The material desired to be displayed is obtained under program control from the input device in which it is deposited. An electronic compositor EC is arranged for translating a stream of computer-coded characters and symbols into a sequence of the appropriate displayable dot patterns. These patterns are obtained from glossaries of display characters placed directly in core storage of a central processing unit CPU. As they are translated, the dot patterns are temporarily stored, a line at a time, in a portion of CPU storage. The lines of dot patterns so stored in the line buffer store are transferred under the control of EC to a circulating store which accommodates one complete frame of image material. This circulating store is read over and over for maintaining a continuous display unless a change in the display is desired. In such a case a whole frame can be replaced or a single character only can be replaced by another.

The top drawing shows an overall system. A glossary of characters to be displayed is stored in file 10. The latter frequently contains one or more courses of instruction for a multiple of students proceeding individually. A transfer is made of either a glossary or a course segment or both from file 10 to CPU 20 of a CAI system. CPU 20 has a storage device with capacity not only for conventional operation but also for the desired number of glossaries, for the line buffer store, and for storing and manipulating a data stream. Input to CPU 20 is provided by station control unit 30 and keyboards 35, arranged for communication with a computing system. Unit 30 selects the proper keyboard 35 and translates the typewriter coded information from the keyboard 35 to CPU 20. The same typewriter coding is used for the digital dot matrix data for forming a desired pattern on a dot matrix modifications of conventional television techniques. Timing waves for a CRT 40 are generated in an associated circuit TC 45. Synchronization of the system is afforded by synchronizing pulses obtained from a circulating storage unit, video buffer VB 50. Control waves for VB 50 are obtained from TC 45 including synchronizing and blanking waves which are mixed in the output circuitry of VB 50. TC 45 and VB 50 also synchronize probe location decoder unit 60. The latter decodes pulse information received from a light probe 65. Such is used to determine the digital coordinates of any position on the screen of a CRT 40 at which a probe 65 is held for another digital input to CPU 20.

EC 70 is coupled between CPU 20 and VB 50 for assembling and transferring lines of binary digital data from CPU 20 to a CRT 40. Control of EC 70 is provided by initialization control unit 82, translate control unit 8...