Abstract: A computer system having a pixel processing unit with multiple subprocessors receives positional data defining graphical objects from the CPU and writes pixel data into the image memory, and a display driver produces an image which partially includes the rendered pixels. The pixel processor is used to access patches of multiple contiguous pixels at a time, and process them in parallel. The patches used are defined, within the overall geometry of the image, to have aligned corners. The unit is also connected to receive synchronization signals from the display driver, conditioned on whether the current line being accessed by the driver is within a specified range of lines in the image space.