US 4,814,756 AGranted

Video display control system having improved storage of alphanumeric and graphic display data

AssigneeTexas Instruments Incorporated

InventorGerard Chauvel

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Abstract

A system for displaying alphanumeric and graphic information on a raster scanned display device, for example, in a teletext system, includes a memory which is updated to change the display. Dynamic changes in the displayed image are provided by assigning a base address to each of one or more zones in the memory and altering the base addresses as required under local or remote control. Alphanumeric and graphic data may be combined on a single displayed page by means of identification data associated with each row or line of data to be displayed. The required capacity of the memory associated with the display device is substantially reduced by assigning a control code to data which is to be repetitively displayed, for example, spaces at the end of a line or fields of uniform color. Selected elements are thus displayed a predetermined number of times without the need for a corresponding number of memory locations. Incoming data may be sotred in a buffer memory at a greater rate than can be processed by the present system by means of a control circuit which inhibits the inputting of data for a period of time when there is a risk of overwriting or erasure of previously stored data.

Claims12

Dependent claims

A display control system comprising:

a first memory means including a plurality of address registers for storing therein page start addresses;
a second memory means including a plurality of page memories, each page memory starting at an address corresponding to the page start address stored in a corresponding address register of said first memory means and having stored therein display data for controlling a page of display, said display data stored in memory zones corresponding to video lines in one of a predetermined set of display modes, said display modes comprising a character mode and a graphics mode, wherein said character mode display data is stored in the form of address words, and wherein said graphics mode display data is stored in the form of a dot pattern, said page memories having further stored therein display mode data which identified the display mode corresponding to individual video lines;
a data processor means connected to said first and second memory means for recalling display data from page memories of said second memory means in accordance with page start addresses stored in said first memory means, said display data thereby recalled in the order of display;
character generator means, coupled to said data processor means and to said second memory means, for storing display data in the form of dot pattern character representations representing a plurality of alpha-numeric characters in locations addressable according to the address words recalled by said data processor means in the character mode;
and
a video control means connected to said second memory means of receiving said recalled dot pattern graphic display data in the graphics mode, and connected to said character generator means for receiving said dot pattern character representations corresponding to address words recalled in the character mode, said video display generator for generating video signals in accordance with said received dot pattern character representations and said dot pattern graphic display data.

3 more elements

A method of displaying graphic and character data by a display control system which displays data on a video display of the raster scan type, said data arranged in a predetermined number of lines corresponding to line sweeps of said video display, said method comprising the steps of:

storing in a page memory the data to be displayed on said video display, said data arranged according to lines of said display and comprising:
for each line of character data, address values corresponding to the addresses of dot matrix character patterns stored in a character generator;
for each line of graphics elements, a dot pattern;
and
for each line of either character data or graphics elements, and identification code indicating whether the next data to be displayed comprises character data or graphic elements;
determining from said identification code if the mode of display for each line sweep is of character or graphics type;
and
if said mode of display for a given line sweep is of character type,
accessing said page memory to obtain the locations in said character generator containing the alphanumeric characters to be displayed;
and
if said mode of display for a given line sweep is of graphics type,
accessing said page memory to obtain the dot pattern for forming the graphic elements to be displayed.

9 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/009,578Filed 28 Jan 1987 · continuation
Priority: FR 80 2639212 Dec 1980
Granted: 21 Mar 1989
Term ends: Not estimatedThe source records don’t support an estimate.

Classification10 codes

G06F 5/14
Means for monitoring the fill level; Means for resolving contention, i.e. conflicts between simultaneous enqueue and dequeue operations: for…
G06F 5/12
Having a sequence of storage locations each being individually accessible for both enqueue and dequeue operations, e.g. using random access…
G09G 5/343
For rolling or scrolling: for systems having a character code-mapped display memory
G09G 5/40
Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators: characterised by the way…