Variable size dot matrix character generator in which a height signal and an aspect ratio signal actuate the same

A variable size character generator used with a system that displays characters as matrices of dots on a screen of a cathode ray tube by modulating a beam of said cathode ray tube, said variable size character generator comprising:

• means for generating width counter signals for counting horizontal segments up to a preselected width;
• means for generating segment height counter signals for counting vertical segments up to a preselected height;
• means for generating scan line counter signals for counting scan lines up to a predetermined segment height;
• means for receiving and storing asynchronously user commands specifying a selected character having a selected height and a selected aspect ratio, said means for receiving and storing responsive to said width counter signals and said segment height counter signals for outputting onto an address bus a character address signal specified by said selected character and for outputting onto a character convertor bus a height signal specified by said selected height and an aspect ratio signal specified by said selected aspect ratio;
• character conversion means for generating scan line signals in response to said scan line counter signals, said segment height counter signals, said height signal and said aspect ratio signal, said scan line control signals reflecting a selected number of lines in a matrix of dots for said selected character to result in a display of said selected character as a matrix of dots having a height defined by said height signal;
• and
• memory means for outputting to a first output a dot matrix stored at a location addressable by said character address signal and said scan line signals, said dot matrix having a fixed number of lines and each of said lines having predetermined dot signals therein, said scan line signals indicating which of said lines is to be outputted to said first output to result in a display of said addressed character as a matrix of dots having a number of lines corresponding to said height signal specified, said scan line signals selectively specifying a plurality of lines for said dot matrix of said character selected corresponding to said fixed number of lines and a plurality of combinations of lines less than said fixed number.

In a system for displaying characters as matrices of dots on a record medium, a method of varying the display size of a selected character, comprising the steps of:

• establishing a height signal and an aspect ratio signal in accordance with a selected height user command and a selected aspect ratio user command, respectively;
• generating scan control signals in accordance with said height signal and said aspect ratio signal;
• determining selected lines of dot signals from a fixed dot matrix of said selected character having a predetermined number of lines of dot signals from a preselected character address of storage means in accordance with said scan control signals and as a function of said height signal;
• developing a dot rate selection signal for defining a width of said selected character in accordance with a selected width as defined by said height signal and said aspect ratio signal;
• supplying a clocking signal whose frequency is selected in response to said dot rate selection signal;
• and
• reading out only said selected lines of dot signals from said fixed dot matrix of said selected character at a rate corresponding to said clocking signal to display said selected character in accordance with the height and width defined by said selected height and aspect ratio user commands.