Display controller for multiple scrolling regions

• US 4,386,410 A
• Filed: 02/23/1981
• Issued: 05/31/1983
• Est. Priority Date: 02/23/1981
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Pandya, Yogendra C., Wood, Paul B.
• Primary Examiner(s): Smith, Jerry
• Application Number:
  US06/237,318
• Time in Patent Office: 827 Days
• Field of Search: 364/200, 364/518, 364/521, 364/900, 340/716, 340/724, 340/726
• US Class Current: 715/201
• CPC Class Codes: G09G 1/007 Circuits for displaying split screens
• CPC Class Codes: G09G 5/14 Display of multiple viewports

Abstract

A display control system which operates asynchronously with a microprocessor includes a display controller, display memory, character memory means, and a visual character attribute generator. By linking one or more row attribute bytes, or pointers, to each row of characters stored in the display memory the display controller performs character and row manipulation on a display device without transferring whole blocks of data in the display memory. Multi-region display segmentation into horizontal and vertical split regions, smooth or discrete scrolling of individual regions, and various editing functions are achieved by modifying the associated display memory pointers. In one embodiment the display controller is a single integrated circuit device.

Claims

1. In a display control system having character memory means, visual attribute generator means, a display device and a display memory, a display controller device comprising:

means for loading character and visual attribute data into selected display memory locations from a data bus, wherein said character data is stored in said character memory means and said attribute data is generated by said visual attribute generator means, and wherein a plurality of character and attribute data bytes form a block of data in the display memory corresponding to a row of characters as seen on the display device;

means for assigning two or more memory location identifier bytes to each displayed row of characters corresponding to and stored adjacent said data blocks in the display memory, wherein when vertical split regions are next to be displayed each of said identifier bytes includes the display memory address of the first character in the next row of characters in a corresponding one of said vertical split regions to be displayed on the display device;

means for storing a data byte corresponding to a preselected column on said display device wherein a vertical split region will begin;

second means for storing a data byte corresponding to the starting address of a character row;

third means for storing a data byte corresponding to the starting row address of a vertical split region; and

means for determining which scan line of a character a particular display memory address corresponds to, whereby a plurality of rows of characters appearing on the display device are scrolled one scan line at a time.

2. The display controller of claim 1 wherein said character memory means comprises a read-only memory, further including:

random access character memory means for storing additional, alterable character data, wherein character data from said random access character means flows through said generator means.

3. In a display control system, a method for displaying data on a display device in a plurality of independently controllable vertically and horizontally segmented regions comprising the steps of:

generating and assigning two or more unique row identifier bytes to each row of data in each of said regions, wherein each of said row identifier bytes indicates the location in a display memory of the first character in the next row of characters in a corresponding one of said vertically or horizontally segmented regions;

interpreting said region row identifier bytes;

accessing the display memory location identified by a particular byte;

displaying the next row of data on said display device; and

repeating said steps of interpreting, accessing and displaying for each frame of data to be displayed on said display device.