Abstract: An embedded modem that does not require a dedicated controller and operates with existing computer to interpret new and redefined communications interrupt requests. In response to an interrupt request, the control of the processor is transferred from the communications software to a driver program stored in the main memory for the processor. Under the operation of the driver program, the processor interprets control characters and causes the appropriate commands to be carried out in the modem. Once these commands have been processed, the control of the processor reverts back to the communications program. The processor thereby functions as a virtual controller that is interpreted to be an external controller by the communications program.

Abstract: A digital display circuit for use with a video game or other displays fabricated as an MOS integrated circuit is described. The circuit permits the simultaneous display of many different patterns (and the simultaneous display of the same pattern) at any locations on a raster scanned cathode ray tube. Content-addressable memories are employed to compare the contents of a digital beam location counter with desired object locations. A random-access memory is then used to address a pattern library where each line of the patterns is stored. When more than one pattern is displayed at the same location, counting in the digital beam location counter is delayed to permit accessing of more than a single pattern line from the pattern library. A displacement counter is employed to store a count representative of the displacement between the actual beam position and the contents of the beam counter. The beam location counter is incremented at a faster rate during non-display periods to compensate for delayed counting.