Abstract: Dot matrix characters are rounded by interpolating quarter dots in the angles of diagonal strokes with the feature that the video signal is a line interlaced signal; the diagonals are detected as predetermined logical combinations of an undelayed signal, a dot-delayed signal, a line delayed signal and a line-plus-dot delayed signal; the quarter dots are interpolated in real time as the diagonals are detected but are interpolated in a first one of the said signals in first fields and in a second one of the said signals in the second, interlaced fields, the second signal being line-delayed relative to the first signal.

Abstract: An analogue-to-digital converter of the parallel-series-parallel type has additional circuitry associated with the second quantization stage which accepts overflow caused by errors in the first quantization stage and generates a correction signal to correct the output of the first quantization stage.

Abstract: In a data display system, data codes are converted by character generators to dot matrix video waveforms for the display of alphanumeric characters and graphical characters (such as segments of graphs or maps), control codes being used to switch between alphanumeric and graphical display modes. In the latter mode, however, certain alphanumeric characters, such as the upper-case alphabet, can still be displayed under the control of a particular bit of the data codes. For one bit value the codes are interpreted as graphical characters. For the other bit value the codes are interpreted as alphanumeric characters.