Apparatus for storing information in and deriving information from a frame buffer

• US 5,241,658 A
• Filed: 08/21/1990
• Issued: 08/31/1993
• Est. Priority Date: 08/21/1990
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Apple Computer Incorporated (Apple Inc.)
• Inventors: Worley, Spencer, Dawson, William, Masterson, Anthony
• Primary Examiner(s): Shaw, Dale M.
• Assistant Examiner(s): Tung, Kee M.
• Application Number:
  US07/570,391
• Time in Patent Office: 1,106 Days
• Field of Search: 395/131, 395/162, 395/164, 395/166, 340/701, 340/703, 340/798-800
• US Class Current: 345/545
• CPC Class Codes: G09G 5/06 using colour palettes, e.g. look-up tables
• CPC Class Codes: G09G 5/391 Resolution modifying circuits, e.g. variable screen formats

Abstract

An arrangement for storing information to be displayed in a plurality of different pixel formats on a bitmapped output display including apparatus for selecting first positions for storage of information in a first pixel format, apparatus for selecting second positions for storage of information in a second pixel format, apparatus for selecting information from first positions of storage for display in the first pixel format, and apparatus for selecting information from second positions of storage for display in the second pixel format.

Claims

1. An arrangement for storing information in a frame buffer, wherein the information is to be displayed in both (1) a twenty-four bit color pixel format and (2) an eight bit pixel format on a bitmapped output display, comprising:

means for selecting first positions for storage of information in the twenty-four bit color pixel format, wherein the means for selecting first positions for storage of information in the twenty-four bit color pixel format comprises

(i) gate array means for transferring color-indicating bits of each pixel to the first positions;

(ii) means for controlling the gate array means to transfer the color-indicating bits of each pixel to the first positions; and

(iii) means for discarding information which does not designate color in pixels of the twenty-four bit color pixel format, wherein the means for discarding information which does not designate color in the pixels of the twenty-four bit color pixel format comprises means for controlling the gate array means to preclude transfer of bits which do not designate color in the pixels of the twenty-four bit color pixel format;

means for selecting second positions for storage of information in the eight bit pixel format;

means for selecting information from the first positions of storage for display in the twenty-four bit color pixel format; and

means for selecting information from second positions of storage for display in the eight bit pixel format.

2. An arrangement for storing information in a frame buffer as claimed in claim 1 in which the means for selecting second positions for storage of information in the eight bit pixel format comprises means for controlling the gate array means to transfer data in the eight bit pixel format to the second positions.

3. An arrangement for storing information in a frame buffer as claimed in claim 2 in which the means for controlling the gate array means to transfer data in the eight bit pixel format to the second positions comprises means for transferring succeeding groups of eight bytes to the same input terminals of the frame buffer.

4. An arrangement for storing information in a frame buffer, wherein the frame buffer can accept ninety-six bits at once, wherein the information is to be displayed in one of (1) a twenty-four bit color pixel format and (2) an eight bit pixel format on a bitmapped output display, wherein the arrangement comprises:

means for selecting first positions for storage of information in the twenty-four bit color pixel format, wherein the means for selecting first positions for storage of information in the twenty-four bit color pixel format comprises

(i) gate array means for transferring color-indicating bits of each pixel to the first positions;

(ii) means for controlling the gate array means to transfer the color-indicating bits of each pixel to the first positions; and

(iii) means for discarding information which does not designate color in pixels of the twenty-four bit color pixel format, wherein the means for discarding information which does not designate color in the pixels of the twenty-four bit color pixel format comprises means for controlling the gate array means to preclude transfer of bits which do not designate color in the pixels of the twenty-four bit color pixel format;

means for selecting second positions for storage of information in the eight bit pixel format;

means for selecting information from the first positions of storage for display in the twenty-four bit color pixel format; and

means for selecting information from the second positions of storage for display in the eight bit pixel format.

5. An arrangement for storing information in a frame buffer as claimed in claim 4 in which the means for selecting second positions for storage of information in the eight bit pixel format comprises means for controlling the gate array means to transfer data in the eight bit pixel format to the second positions.

6. An arrangement for storing information in a frame buffer as claimed in claim 5 in which the means for controlling the gate array means to transfer data in the eight bit pixel format to the second positions comprises means for transferring succeeding groups of eight bytes to the same input terminals of the frame buffer.