Variable size character raster display

Claim 1

Apparatus for generating from a first plurality of coded input data character signals a television compatible composite video output signal for application to a television receiver to provide a visible display of a first plurality of data characters in a second plurality of data lines, each data line formed of a third plurality of scan lines, each scan line including a fourth plurality of data bits, said apparatus comprising: a. clock means for generating clock pulses of a first frequency; b. first counting means connected to said clock means and responsive to said clock pulses for counting scan lines and providing an indication thereof; c. second counting means connected to said clock means and responsive to said clock pulses for counting display lines and providing an indication thereof; d. third counting means connected to said clock means and responsive to said clock pulses for counting characters in each display line and providing an indication thereof; e. gating means having an output and having a first plurality of inputs adapted for connection to a first plurality of data sources for receipt in parallel therefrom of a first plurality of coded input data characters, said gating means having further inputs connected to said second and third counting means and in response to display line number indications and character number indications sequentially providing said first plurality of coded input data character signals as a coded output data chaRacter signal; f. decoding means connected to said gating means and to said first counting means and responsive to said coded output data character signal and to scan line number indications for decoding said coded output data character signal into a fourth plurality of data bits representative of the indicated scan line of the output data character of said coded output data character signal; g. video signal generator means connected to said decoding means and to said first, second and third counting means and in response to said fourth plurality of data bits and to scan line number indications, display line number indications, and character number indications generating as a television compatible composite video output signal the indicated scan line of the output data character of said coded output data character signal; and h. first control means for causing said clock means to generate clock pulses at a second frequency less than said first frequency and for causing said first and second counting means to change the scan line number and display line number less frequently, whereby the visible display is of increased size.