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. For representation of a single dot portion of one of the characters or symbols, a pair of video data bits is stored to generate a pair of horizontally disposed pels on the display when the character or symbol is displayed in the shorter of the two vertical heights. Translation logic is described to efficiently provide for two sizes of characters with a minimum of additional hardware and with no additional character generator memory beyond that required for the smallest characters or symbols.
A data display arrangement in which each of a number of different characters displayed on a CRT is defined by selected dots of a dot matrix. The stored character information from which character generating signals are produced is in the form of corresponding memory cell bit matrix. Such character information is read-out once in a number of successive scanning lines of each field to display the character normal height, and hitherto has been read-out twice in a number of successive pairs of scanning lines of each field to display the character double height. The invention provides a "double height algorithm" which modifies the read-out for double height character display such that part of a memory cell is read-out once and part is read-out twice. This results in a non-linear expansion of a double height character the effect of which is to maintain the visual baseline of a character row. With respect to a simple expansion, the enlarged character is "pushed down" by a number of scanning lines thus maintaining the baseline. Any part of a character below the baseline is "compressed" into the space below it. FIG. 2 shows examples of displayed characters.
A display device comprises a memory for storing article name data first and second character generators, a display unit, and a control unit. The character generators respectively generate character data of a normal character size and also of a character size smaller than the normal character size. The control unit detects the number of characters of the article name data stored in the memory, causing the character generators to generate character data, according to the stored article name data, of the smaller character size or of the normal character size, depending on whether the detected number of characters is greater or less than a predetermined value. The generated character data is displayed on the display unit.
A display apparatus for displaying character information in various modes. This display apparatus allows the display modes to be changed by changing a character size and a display start address without changing the relative position of a cursor.
An alpha-numeric character generator arrangement having a character store (ROM) in which characters are stored in a character format contained within a co-ordinate character matrix of 10.times.6 discrete character elements. For television interlaced display using a 625-line standard, whole character shapes are displayed in both odd and even fields. For television interlaced display using a 525-line standard, only partial character shapes are displayed in each field, by omitting certain character element rows which are different for each field. The stored character set is so chosen in relation to the omitted character element rows that flicker is minimized. The reduced sized characters, as displayed, allow the same number of rows of characters per frame for the 525-line standard as for the 625-line standard.
A display system using a matrix of rotatable display elements is provided in which the optical states of the display elements can be read back to confirm that the matrix is portraying information correctly. The display system is arranged to automatically ameliorate the effect of detected non-operating display elements on the intelligibility of the message displayed.
