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
Selecting from a plural of energy saving modes
Method of synchronization for low power idle
Lettuce sister lines PX06514083, PX06514153, PX06514201 and PX06514204
System and method for broadcasting rich media to devices over multiple carriers
Bacterial superantigen vaccines
Analysis of methylation using nucleic acid arrays
  Randomly Featured Patents
Method and apparatus for the detection and regeneration of a lost token in a token based data communications network
Parking aid for a motor vehicle having sensors with substantially the same detection area
Dual anchoring tubular back-off tool
Radial tire for heavy load with specified metal carcass cord
Medical tape preparation
Apparatus for detecting malfunction in cyclically repetitive processes in an internal combustion engine
Process for producing lightweight thermoplastic composite products in a continuous manner
Scale balancing device in universal parallel ruler device
Fluid collection, storage and infusion apparatus
Method of forming internal spline shaft