Abstract: A processor controlled character box display is provided with apparatus which permits the display of curvilinear graphics. The characters used to generate the graphics display are selected from a limited character set in read only storage (46), but by shifting the characters up or down by less than a full line index to provide additional character positions, it is possible to produce curvilinear graphics without the need for further character generation. Since the graphics display is a low resolution display, it is necessary to make a best dot selection in order to map the print bit map into the character box display.

Abstract: A technique for displaying a representation of a full page on less than an entire CRT screen in a word processing system. The full page representation uses character indicators to enable the word processing system user to appreciate format and spatial relationships with regard to page boundaries. Within the miniature page the interlinear spacing chosen by the operator for the hard copy output is properly represented. Integral line spacing is achieved by displaying blank lines as appropriate. Non-integral line spacing such as half-line spacing is achieved advantageously through manipulating the particular character construct utilized. A character representation matrix is usually blank at the top and blank or non-blank in the bottom half. Reversing top and bottom halves removes one half-line of interlinear spacing.

Abstract: There is described a technique for use in a word processing system for displaying a representation of the full page of text on less than an entire CRT screen where the full page representation is proportional to the hard copy output which eventually results. Dynamic mode switching is employed which enables the output on a given line of the display of both full size characters and miniature character representations. Dynamic mode switching also provides control of the placement of the miniature page representation on the CRT screen.

Abstract: A display refresh system wherein a RAM refresh buffer is tightly packed. Line start addresses in the buffer are determined by the line length such as eighty characters. With each of the lines in the refresh buffer being normally a binary number such as 128 characters in length the line start addresses are such that they do not coincide with the beginning of each line in the buffer. To assure packing they are interspersed each 80 positions sequentially within the buffer. A processor loads the address of each line start character into the pointer area of the refresh buffer. A line counter is used which counts the lines being displayed on the display. The RAM refresh buffer which contains the line start addresses and character data is first addressed by the line counter output to provide the line address. Since the refresh buffer is used as the line pointer register the output bus for pointer data and character data is common.

Abstract: A system and method for generating properly proportioned alphanumeric characters and symbols in two vertical heights with a single character generator and a minimum of associated circuitry. The bits of video data stored in the character generator are stored such that the vertical segments of diagonal portions of the characters and symbols include no more than two bits per vertical segment of the diagonal portion. The video data bits representative of the pels of circular portions of the symbols are stored in an arrangement to generate a horizontally elongated elliptical shape when the character or symbol is displayed in the shorter of the two heights. Whenever possible, the diagonal portions of characters include no more than two diagonally disposed pels in the single high character size.