Resources Contact Us Home
Video memory system

Image Number 6 for United States Patent #4644495.

An improved video memory system includes a program memory, a display data memory, and a plurality of data fetchers. The data fetchers are used to indirectly address the display data in the display data memory. The data fetchers are programmed during vertical blanking so that selected display data is fetched at selected vertical display positions. During each scan line each data fetcher is "read" by: (1) decrementing a counter in the data fetcher; (2) comparing the counter value against preselected top and bottom values; and (3) using the counter value to indirectly address display data that is to be displayed on the current scan line if the counter value is between the top and bottom values. This relieves the host computer of having to keep track of the current vertical display position, thereby freeing it to use the saved computer cycles to produce more interesting viedo games with more complex display graphics. In addition there are provided data fetchers that can be programmed to periodically issue signals usable either for drawing a line with a predefined slope or modulating the amplitude of a sound generator.

  Recently Added Patents
Methods and apparatus to provide haptic feedback
Portable electronic device housing including hinge
Rechargeable battery
OFDM control signaling in the presence of timing asynchronization in a peer-to-peer network
Semiconductor fin device and method for forming the same using high tilt angle implant
Circuitry for measuring and compensating phase and amplitude differences in NDT/NDI operation
Near-field optical disk having surface plasmon amplification by stimulated emission of radiation
  Randomly Featured Patents
Optimized field-frame prediction error calculation method and apparatus in a scalable MPEG-2 compliant video encoder
Decoration board for electric wire laid
Radio frequency connector for a patch coupled aperture array antenna
Method and cooler for cooling particulate material
Rotary developing device for an image forming apparatus
Negative voltage generator
Spool packaging member and method
Apparatus for unscrambling and erecting a plurality of non-vertical bottles
Cage apparatus for printed circuit boards and method for preventing sharp spikes in the signal applied to said printed circuit boards