Abstract: A method of electronically moving portions of several different images on a CRT screen includes the steps of: storing a first image in one section of an image memory, and storing a second image in a different section of the image memory; storing control bits in a control memory which define high and low priority viewports on the screen and correlate portions of the first and second images to the high and low priority viewports respectively; displaying, in response to the stored control bits, the entire portion of the image in the high priority viewport and only the non-overlapping portion of the image in the low priority viewport by transferring the image portions from the image memory to the screen with no frame buffer therebetween; modifying at least some of the stored control bits to change the priorities of the high and low priority viewports to low and high respectively; and repeating the displaying step, in response to the modified control bits, to display the entire portion of the image in the new high

Abstract: A system for electronically displaying multiple images on a CRT screen such that some of the images are more prominent than others comprises: a control memory for storing control signals which partition the screen into an array of blocks, define multiple prioritized viewports by indicating which blocks are included in each viewport, and correlate respective image pixels to each viewport; a circuit for determining, from the control signals, the identity of the highest priority viewport to include a particular block; a plurality of color map memories each of which contains a plurality of color signals; a correlator for addressing a particular color map memory of said plurality based on the identity of the highest priority viewport; and a circuit for transferring respective color signals from the addressed color map memory to the screen based on the image pixels in the block of the highest priority viewport.

Abstract: A system for electronically displaying portions of several different images on a CRT screen comprises: a memory for storing a complete first image as several pixels in one section of the memory and a complete second image as several other pixels in another section of the memory such that the total number of stored pixels is substantially larger than the number of pixels on the screen; a logic circuit for reading a sequence of the pixels at non-contiguous locations in the first and second images and for transferring them, in the sequence in which they are read, to the screen for display with no frame buffer therebetween; the logic circuit for reading including a module for forming non-contiguous addresses for the pixels in the sequence in which they are read with the address of one word of pixels being formed during the time interval that a previously addressed word of pixels is being displayed on the screen.