Abstract: A computer system that provides for transparent plugging and unplugging of a keyboard independent of system operation. A virtual keyboard device communicates with the system keyboard controller when no keyboard is plugged. The virtual keyboard device provides appropriate responses to inquiries from the operating system during startup, allowing the system to boot without an actual keyboard being present. When a keyboard is plugged, its presence is detected and it is configured by a virtual keyboard controller. The newly configured keyboard is then coupled to the system keyboard controller. On unplug, the lack of a keyboard is detected by monitoring the power supply to the keyboard, whereupon the virtual keyboard is again coupled to the system keyboard controller.

Abstract: The present invention is a graphics subsystem with a plurality of storage elements addressed by multiple bit physical addresses and a video display with a plurality of pixels addressed by multiple bit logical addresses. The graphics subsystem includes an address conversion circuitry for converting the logical addresses of the pixels to physical addresses in the video memory. When the number of bytes needed to address the plurality of pixels across the screen is not equal to an integral power of two and the logical addresses of the plurality of pixels are arranged in tiles, the address conversion circuitry converts the logical addresses of the pixels to physical addresses in the video memory by converting only portions of the total address space into tiles at any one time.