Apparatus for displaying characters and/or limited graphs

Claim 1

An apparatus for displaying characters and limited graphs on a cathode ray tube of a standard television system, each character being displayed at a character area on said cathode ray tube, which character area is divided into (S-1) blocks for picture element display, the apparatus comprising: an input-output circuit; a refresh memory circulating at a clock frequency; a character generator; a picture element generator; means coupled to said input-output circuit and said refresh memory for entering character codes of plural lines from said input-output circuit into said refresh memory, each character code being formed by S bits, one of which is a discrimination bit for discriminating whether to drive said character generator or to drive said picture element generator and the others of which correspond to said (S-1) blocks of each character area; a shift register operatively coupled to said character generator and said picture element generator; and means coupled to said shift register and said refresh memory for transferring said character codes to said shift register from said refresh memory, said character generator beiNg driven in accordance with the value of said discrimination bit of the output signals produced by said shift register for converting said output signals into video signals which produce character patterns on said cathode ray tube, said picture element generator being driven in accordance with the value of said discrimination bit of the output signals produced at said shift register for converting said output signals produced at said shift register into video signals which produce picture element patterns on said cathode ray tube, whereby when it is determined in accordance with the discrimination bit in each of some predetermined character codes to drive said picture element generator, said picture element generator is driven by the output signals produced at said shift register and generates picture elements in some blocks of predetermined character areas in accordance with the value of each of said (S-1) bits of said some predetermined character codes so as to enable a display of a limited graph on said cathode ray tube, so that characters and limited graphs in a predetermined pattern can be displayed on said cathode ray tube.

Claim 2

An apparatus for displaying characters and limited graphs on a cathode ray tube of a standard television system, each character being displayed at a character area on said cathode ray tube, which character area is divided into (S-1) blocks for picture element display, the apparatus comprising: an input-output circuit; a refresh memory circulating at a clock frequency; a character generator; a picture element generator; means coupled to said input-output circuit and said refresh memory for entering character codes of plural lines from said input-output circuit into said refresh memory, each character code being formed by S bits, one of which is a discrimination bit for discriminating whether to drive said character generator or to drive said picture element generator and the others of which correspond to said (S-1) blocks of each character area; a shift register operatively coupled to said character generator and said picture element generator; and means coupled to said shift register and said refresh memory for transferring said character codes to said shift register from said refresh memory, said character generator beiNg driven in accordance with the value of said discrimination bit of the output signals produced by said shift register for converting said output signals into video signals which produce character patterns on said cathode ray tube, said picture element generator being driven in accordance with the value of said discrimination bit of the output signals produced at said shift register for converting said output signals produced at said shift register into video signals which produce picture element patterns on said cathode ray tube, whereby when it is determined in accordance with the discrimination bit in each of some predetermined character codes to drive said picture element generator, said picture element generator is driven by the output signals produced at said shift register and generates picture elements in some blocks of predetermined character areas in accordance with the value of each of said (S-1) bits of said some predetermined character codes so as to enable a display of a limited graph on said cathode ray tube, so that characters and limited graphs in a predetermined pattern can be displayed on said cathode ray tube.