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
Event handling in an integrated execution environment
Quick mounting device
System and method for reducing the risks involved in trading multiple spread trading strategies
Distortion estimation for quantized data
System and method for secure power systems infrastructure communications
Piezoelectric speaker and method of manufacturing the same
Semiconductor assembly and semiconductor package including a solder channel
  Randomly Featured Patents
Information signal reproducing apparatus in which control signal condition and information signal level are varied so as to correspond
Protective arrangement for a longitudinally extendible machine component
Method for reconditioning a propane gas tank
Method and apparatus for thermal isolation of a gas sensor
Charger unit
Surgical retaining device
Support for an artificial plant, tree, or the like
Methods and apparatus for removal of films and flakes from the edge of both sides of a substrate using backing pads
Occupant detecting seat assembly with headrest and method of moving headrest