Character generator

Abstract

A character generator produces highly accurate electronic reproductions of characters of any chosen style on the screen of a CRT by simultaneously controlling the orientation, length and intensity of the strokes formed by the electron beam of the CRT. The character generator is coupled to an input source which periodically generates a character address signal representative of a selected character. A read only memory contains a plurality of multi-byte microprograms each located at a predetermined address. Twelve eight-bit bytes constitute a single microprogram which defines a single character. A single byte of a microprogram defines a single stroke of a character. A first three-bit element of each byte fully defines the magnitude and polarity of the X component of the stroke, while a second three-bit element of the byte defines the magnitude and polarity of the Y component of the stroke. The remaining two-bit element of the byte designates one of four available electron beam intensity levels. The read only memory sequentially reads out each byte of the microprogram designated by each sequentially received character address signal. A set of digital to analog converters converts the sequentially generated bytes from the read only memory into three independent analog signals. These analog signals control the intensity and position of the electron beam which reproduces the selected character on the screen of the CRT by forming variable length, constant intensity strokes in the pattern determined by each selected microprogram.