A MOS cursive-character generator [for deflection system of CRT graphic display

Abstract

Cursive characters can be made to be more readable, more attractive, and better suited to the operation of graphic CRT terminals than the usual dot-matrix type; a system using cursive-type characters achieves much higher writing rate while requiring much less bandwidth than that using dot-matrix-type characters. An economical method of generating the x, y, and z analog signals for forming cursive characters with the deflection system of a CRT is presented. A circuit design embodying a complete 48-stroke character generator on a single MOS integrated circuit is described. The IC accepts 7-bit ASCII code and outputs x, y, and z analog signals to generate any one of 32 standard ASCII characters in 5 /spl mu/s. Additional groups of 32 characters can be added by merely paralleling additional chips. The entire 32 character digital and analog function has been implemented on a single self-contained 16-pin silicon-gate MOS chip 125/spl times/165 mil in size. Character encoding on the chip is accomplished in one mask at the diffusion step, and a straightforward mask-generation procedure has been developed.