Browse Prior Art Database

Formattable Video Band Display

IP.com Disclosure Number: IPCOM000086351D
Original Publication Date: 1976-Aug-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 4 page(s) / 63K

Publishing Venue

IBM

Related People

Chesarek, DJ: AUTHOR

Abstract

This display requires refresh buffering for only those raster scan lines which are part of an image field, and provides for formatting of both the alphanumeric (A/N) and image information shown on the display.

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Formattable Video Band Display

This display requires refresh buffering for only those raster scan lines which are part of an image field, and provides for formatting of both the alphanumeric (A/N) and image information shown on the display.

Each collection of adjacent scan lines used to present image information on the display is called a video band. The image content need not occupy the full width of a band and, in fact, a facility is provided to place several small video images into a single band in order to make better utilization of the information display potential of each video band.

The formatting of information on the display screen is accomplished through the use of two relocate tables: a scan line relocate table for video bands and an A/N line relocate for A/N lines of information.

Referring to Fig. 1, the information shown on the video display 10 is refreshed from two sources on a time/space multiplex basis. A/N information via "on-the-fly" character generation 14, an A/N data memory 16 and image information from an image data memory 12. The structure of the A/N refresh data flow is identical to that found in many raster based cathode-ray tube (CRT) displays, except for the inclusion of an A/N line relocate table. The structure of the image information refresh process is simply data transfer from image data memory 12 to CRT, on a scan line basis, with scan line address mapping provided by a scan line relocate table.

The display is programmed (by appropriate loading of the relocate tables) to have three video bands and four lines of A/N information. Note that at the bottom of the display screen image information and A/N information coexist on a collection of scan lines. This is possible because the A/N information and image information sources are independent, but driven from a common set of timing logic circuitry.

Figs. 2a and 2b show the logical contents of both the A/N line relocate table and the image scan line relocate table. Note that the image scan line relocate table not only establishes the starting scan line for each video band but also the number of scan lines in each band.

The "host" system transfers image information to the image data memory 12 as though it would produce a continuous set of scan lines on the display. Display refresh logic relocates scan lines on the display under control of the scan line relocate table (whose contents were established under host system control). The sequence of information loading and control would be as follows: 1. Display = Blank (Control). 2. Transfer Image Data to Image Data Memory. 3. Load Scan Line Relocate Table. 4. Transfer A/N Data to A/N Data Memory. 5. Load A/N Line Relocate Table. 6. Display = Active (Control-Activate Refresh Process).

The operator can at the conclusion of step 6, interact with the display in a manner consistent with usual display practice (e.g., update A/N data via a keyboard, select information on the screen with a light pen, etc.). A light pen...