Character generation system for a visual display terminal

Claim 1

A system for intensifying and displaying dot-matrix characters of the type which includes a read-only memory for storing at addressable locations therein a plurality of characters, each said character being defined by a plurality of signals representative of Y rows and X columns of lighted discrete dot patterns to be displayed on a cathode ray tube, and memory addressing means for selecting one of said plurality of said characters, the improvement comprising: a ready-only memory for receiving an address indicative of a character to be displayed and for generating a plurality of parallel signals representative of the Y row of dots of said dot-matrix character to be displayed, timing means, including row counting means, connected to said read-only memory for producing a discrete Y count of the row of dots of said dot-matrix character to be displayed, a Y row register connected to said read-only memory for receiving and storing said plurality of signals representative of said Y row of said discrete rows of dots being generated by said read-only memory, said Y row register being connected to the intensity grid of said cathode ray tube for indicating the absence or presence of signals representative of lighted dots of said dot-matrix character, scanning means for gating one of said signals from said Y row a column at a time to said cathode ray tube intensity grid, character row storage means for receiving and storing a plurality of signals representative of a Y + 1 row of said discrete rows of dots of said dot-matrix character to be displayed, said character row storage means being connected to said read-only memory, said row counting means comprising row counter advance means connected intermediate said read-only memory and said timing means for producing a Y + 1 count of the row of dots of said dot-matrix character to be displayed, a Y + 1 row register connected to said character row storage means for receiving and storing said plurality of signals representative of the Y + 1 row of said discrete rows of dots being generated by said character row register, and logic means connected intermediate said scanning means and said row registers for comparing the signals stored at the same column of said Y row and said Y + 1 row and for generating an intensifying signal representative of a dot to be inserted between said rows of adjacent dots in said dot matrix pattern.

Claim 2

A system for intensifying and displaying dot-matrix characters of the type which includes a read-only memory for storing at addressable locations therein a plurality of characters, each said character being defined by a plurality of signals representative of Y rows and X columns of lighted discrete dot patterns to be displayed on a cathode ray tube, and memory addressing means for selecting one of said plurality of said characters, the improvement comprising: a ready-only memory for receiving an address indicative of a character to be displayed and for generating a plurality of parallel signals representative of the Y row of dots of said dot-matrix character to be displayed, timing means, including row counting means, connected to said read-only memory for producing a discrete Y count of the row of dots of said dot-matrix character to be displayed, a Y row register connected to said read-only memory for receiving and storing said plurality of signals representative of said Y row of said discrete rows of dots being generated by said read-only memory, said Y row register being connected to the intensity grid of said cathode ray tube for indicating the absence or presence of signals representative of lighted dots of said dot-matrix character, scanning means for gating one of said signals from said Y row a column at a time to said cathode ray tube intensity grid, character row storage means for receiving and storing a plurality of signals representative of a Y + 1 row of said discrete rows of dots of said dot-matrix character to be displayed, said character row storage means being connected to said read-only memory, said row counting means comprising row counter advance means connected intermediate said read-only memory and said timing means for producing a Y + 1 count of the row of dots of said dot-matrix character to be displayed, a Y + 1 row register connected to said character row storage means for receiving and storing said plurality of signals representative of the Y + 1 row of said discrete rows of dots being generated by said character row register, and logic means connected intermediate said scanning means and said row registers for comparing the signals stored at the same column of said Y row and said Y + 1 row and for generating an intensifying signal representative of a dot to be inserted between said rows of adjacent dots in said dot matrix pattern.

Claim 5

A system for intensifying and displaying dot-matrix characters of the type which includes a read-only memory for storing at addressable locations therein a plurality of characters, each said character being defined by a plurality of signals representative of Y rows and X columns of lighted discrete dot patterns to be displayed on a cathod ray tube, and memory addressing means for selecting one of said plurality of said characters, the improvement comprising: a read-only memory for receiving an address indicative of a character to be displayed and for generating a plurality of parallel signals representative of the Y row of dots of said dot-matrix character to be displayed, timing means, including row counting means, connected to said read-only memory for producing a discrete Y count of the row of dots of said dot-matrix character to be displayed, a Y row register connected to said read-only memory for receiving and storing said plurality of signals representative of said Y row of said discrete rows of dots being generated by said read-only memory, said Y row register being connected to the intensity grid of said cathode ray tube for indicating the absence or presence of signals representative of lighted dots of said dot-matrix, scanning means for gating one of said signals of said Y row a column at a time to said cathode ray tube intensity grid, a second read-only memory for receiving said address indicative of a character to be displayed and for generating a plurality of parallel signals representative of one of said discrete rosw of dots of said dot-matrix character to be displayed, said row counting means comprising row counter advance means connected intermediate said second read-only memory and said timing means for producing a Y + 1 count of the row of dots of said dot-matrix character to be displayed, a Y + 1 row register connected to said second read-only memory for receiving and storing said plurality of signals representative of the Y + 1 row of said discrete rows of dots being generated by said second read-only memory, and logic means connected intermediate said scanning means and said row registers for comparing the signals stored at the same column of said Y row and said Y + 1 row and for generating an intensifying signal representative of a dot to be inserted between said rows of adjacent dots in said dot matrix pattern.

Claim 6

A system for intensifying and displaying dot-matrix characters of the type which includes a read-only memory for storing at addressable locations therein a plurality of characters, each said character being defined by a plurality of signals representative of Y rows and X columns of lighted discrete dot patterns to be displayed on a cathod ray tube, and memory addressing means for selecting one of said plurality of said characters, the improvement comprising: a read-only memory for receiving an address indicative of a character to be displayed and for generating a plurality of parallel signals representative of the Y row of dots of said dot-matrix character to be displayed, timing means, including row counting means, connected to said read-only memory for producing a discrete Y count of the row of dots of said dot-matrix character to be displayed, a Y row register connected to said read-only memory for receiving and storing said plurality of signals representative of said Y row of said discrete rows of dots being generated by said read-only memory, said Y row register being connected to the intensity grid of said cathode ray tube for indicating the absence or presence of signals representative of lighted dots of said dot-matrix, scanning means for gating one of said signals of said Y row a column at a time to said cathode ray tube intensity grid, a second read-only memory for receiving said address indicative of a character to be displayed and for generating a plurality of parallel signals representative of one of said discrete rosw of dots of said dot-matrix character to be displayed, said row counting means comprising row counter advance means connected intermediate said second read-only memory and said timing means for producing a Y + 1 count of the row of dots of said dot-matrix character to be displayed, a Y + 1 row register connected to said second read-only memory for receiving and storing said plurality of signals representative of the Y + 1 row of said discrete rows of dots being generated by said second read-only memory, and logic means connected intermediate said scanning means and said row registers for comparing the signals stored at the same column of said Y row and said Y + 1 row and for generating an intensifying signal representative of a dot to be inserted between said rows of adjacent dots in said dot matrix pattern.

Claim 13

A method of converting the output of an X × Y dot-matrix character generator to a (2X - 1) × (2Y - 1) dot-matrix output comprising the steps of: generating an X × Y dot-matrix pattern from an X × Y dot-matrix character generator one row at a time, displaying said X × Y dot-matrix pattern on a first pass raster scan of a visual display terminal to provide X × Y dot-matrix characters, generating two discrete row patterns of said X × Y dot-matrix pattern, storing said two discrete row patterns of said dot-matrix pattern in storage means, logically comparing said two discrete row patterns of said dot-matrix pattern stored in said storage means, generating a plurality of dots according to said logical comparison of said two discrete row patterns of said dot-matrix pattern, and displaying said plurality of dots generated according to said logical comparison on a second pass raster scan of said visual display terminal, said second pass raster scan being interlaced between said first pass raster scan of said visual display terminal to provide (2X - 1) × (2Y - 1) dot-matrix characters.

Claim 14

A method of converting the output of an X × Y dot-matrix character generator to a (2X - 1) × (2Y - 1) dot-matrix output comprising the steps of: generating an X × Y dot-matrix pattern from an X × Y dot-matrix character generator one row at a time, displaying said X × Y dot-matrix pattern on a first pass raster scan of a visual display terminal to provide X × Y dot-matrix characters, generating two discrete row patterns of said X × Y dot-matrix pattern, storing said two discrete row patterns of said dot-matrix pattern in storage means, logically comparing said two discrete row patterns of said dot-matrix pattern stored in said storage means, generating a plurality of dots according to said logical comparison of said two discrete row patterns of said dot-matrix pattern, and displaying said plurality of dots generated according to said logical comparison on a second pass raster scan of said visual display terminal, said second pass raster scan being interlaced between said first pass raster scan of said visual display terminal to provide (2X - 1) × (2Y - 1) dot-matrix characters.