EP 0392551 A2 19901017 - Window priority encoder.
Title (en)
Window priority encoder.
Title (de)
Prioritätskodiereinrichtung für Fenster.
Title (fr)
Codeur de priorité pour fenêtres.
Publication
Application
Priority
US 33830189 A 19890414
Abstract (en)
Color index data for a first image and one or more second images is stored in a frame buffer memory and is introduced to an address register of a color palette random access memory. The data from the second images is to be displayed in separate windows on a visual display screen. The palette memory addresses selected by the color index data contain digital information determining the true color to be displayed in each window. Such is introduced to a different range of palette memory addresses. Data from a microprocessor bus indicating the start-stop coordinates of each second image window in coordinate directions is introduced to comparison registers for the palette random access memory. Because windows may overlap, each window is assigned a priority according to the identity of the register containing the start-stop coordinates of the window. These control registers provide, to the palette memory address register, additional address data that is combined with the color index data and introduced to an address decoder that selects the desired palette location. Thus the register data determines the range of palette memory addresses to be selected and the color index data determines the palette location within the range. The true color data in each palette location can be updated at any time by microprocessor data introduced to a slow port. Additional microprocessor data introduced to the control registers can cause a flood color pallet address to be accessed when the display is within the start and stop coordinates of a given window. This flood color may be used to mask the display of the image in the frame buffer when it is being modified.
IPC 1-7
IPC 8 full level
G06F 3/14 (2006.01); G06T 11/00 (2006.01); G09G 5/06 (2006.01); G09G 5/14 (2006.01)
CPC (source: EP)
Designated contracting state (EPC)
AT BE CH DE ES FR GB GR IT LI LU NL SE
DOCDB simple family (publication)
EP 0392551 A2 19901017; EP 0392551 A3 19910925; CA 2013615 A1 19901014; CA 2013615 C 20001212; JP H03206492 A 19910909
DOCDB simple family (application)
EP 90107080 A 19900412; CA 2013615 A 19900402; JP 9662890 A 19900413