Hardware implementation for providing raster offsets in a graphics subsystem with windowing

Claim 1

An apparatus for converting pairs of original X and Y coordinates of an object to be displayed by a graphics subsystem to pairs of window coordinates for display within an active window, said window coordinates having a predetermined X offset and a predetermined Y offset from said original X and Y coordinates, said conversation being an addition of said original X and Y coordinates to said predetermined X offset and said predetermined Y offset, respectively, said object being one of a quadrilateral to be drawn and a block image to be moved, said apparatus comprising: a) a pair of raster offset registers for storing said predetermined X offset and sad predetermined Y offset; b) a plurality of object coordinate registers for storing the sum of respective pairs of said X and Y object coordinates and said predetermined X offset and Y offset; c) loading control means coupled to an indexing register for controlling the loading of said pair of offset registers with said predetermined X offset and said predetermined Y offset and said plurality of object coordinate registers with said sum; d) input means coupled to said loading control means, said object coordinate registers and said raster offset registers for receiving from a source external to said apparatus, said X and Y object coordinates and said predetermined X and Y raster offsets, and for storing said predetermined X offset and said predetermined Y offset in said raster offset register and for adding said predetermined X offset and said predetermined Y offset in said raster offset registers to said X and Y object coordinates in said object coordinate registers; said graphics subsystem for displaying said object which is represented by said sums stored in said object coordinate registers.

Claim 2

An apparatus for converting pairs of original X and Y coordinates of an object to be displayed by a graphics subsystem to pairs of window coordinates for display within an active window, said window coordinates having a predetermined X offset and a predetermined Y offset from said original X and Y coordinates, said conversation being an addition of said original X and Y coordinates to said predetermined X offset and said predetermined Y offset, respectively, said object being one of a quadrilateral to be drawn and a block image to be moved, said apparatus comprising: a) a pair of raster offset registers for storing said predetermined X offset and sad predetermined Y offset; b) a plurality of object coordinate registers for storing the sum of respective pairs of said X and Y object coordinates and said predetermined X offset and Y offset; c) loading control means coupled to an indexing register for controlling the loading of said pair of offset registers with said predetermined X offset and said predetermined Y offset and said plurality of object coordinate registers with said sum; d) input means coupled to said loading control means, said object coordinate registers and said raster offset registers for receiving from a source external to said apparatus, said X and Y object coordinates and said predetermined X and Y raster offsets, and for storing said predetermined X offset and said predetermined Y offset in said raster offset register and for adding said predetermined X offset and said predetermined Y offset in said raster offset registers to said X and Y object coordinates in said object coordinate registers; said graphics subsystem for displaying said object which is represented by said sums stored in said object coordinate registers.