example semiconductor memory devices such as eprom eeprom and flash memory devices magnetic disks such as internal hard disks and removable disks magneto optical disks and cd rom disks any of the foregoing can be supplemented by or incorporated in asics application specific integrated circuits fig5 shows a computer system 500 employed to implement the invention the computer system 500 is only an example of a graphics system in which the present invention can be implemented the computer system 500 includes a central processing unit cpu 510 a random access memory ram 520 a read only memory rom 525 one or more peripherals 530 a graphics controller 560 primary storage devices 540 and 550 and a digital display unit 570 as is well known in the art rom acts to transfer data and instructions uni directionally to the cpus 510 while the ram 520 is used typically to transfer data and instructions in a bi directional manner the cpus 510 can generally include any number of processors both primary storage devices 540 and 550 can include any suitable computer readable media a secondary storage medium 580 which is typically a mass memory device is also coupled bi directionally to the cpus 510 and provides additional data storage capacity the mass memory device 580 is a computer readable medium that can be used to store programs including computer code data and the like typically the mass memory device.