Patent GB-1386884-A (GB)
Title: Character display system
IPC: G06F3/02
Filed: 1972-07-24
Abstract: 1386884 Cathode-ray tube displays MATSUSHITA ELECTRIC INDUSTRIAL CO Ltd 24 July 1972 [27 July 1971 6 Aug 1971 31 Aug 1971(2) 7 Sept 1971 (2) 15 Oct 1971] 34578/72 Heading H4T In a cathode-ray tube character display system in which 6 bit data words control a character generator (see Fig. 1) producing video signals for intensity control of a line scanned raster to display 16 lines each of 64 characters (see Fig. 2) six registers (only three shown) REL1, RFL2 ... RFL6 each hold 64 bits (specifying in parallel, 64 characters) these bits being supplied sequentially in parallel to the character generator and via respective gates (only three shown) CG1, CG2 ... CG6 recirculated in the registers RFL1 ... RFL6 to produce one line of characters after which, by selective operation of the gates CG1 ... CG6 and of further gates (only three shown) 1G1 ... 1G6 the data in registers RFL1, &c. are transferred to respective registers (only three shown) RFP1 ... RFP6 as their contents, comprising for each register, 64 x 15 = 960 bits i.e. data for all but one line (that held in registers RFL, &c.) of the display, are transferred via the gates IG, &c. to the registers RFL, &c. Each line of characters requires ten horizontal scanning lines of which the first seven are employed to form the characters, the eight line to provide a space between the characters and a cursor (see Fig. 2), which requires a further line (the ninth) and the tenth line then provides a space between the cursor and the succeeding line of characters (see Fig. 3). In the operation of the arrangement signals from a control circuit CB on lines X and Y control the gates CG1 &c. such that the signal on line Y causes recirculation of the data in registers RFL1 &c. alone during scan lines 1 to 9 whilst the signal on line X causes recirculation of the data in registers RFH, &c. and RFP1, &c. to refresh the whole display. The cursor data is introduced via gate IPG and gates IGI, &c. at an address determined by a signal on line K in accordance with a keyboard operated control and other data from the keyboard may be introduced directly via the gates IGI, &c. A main feature of the system described above consists of the provision of means for changing the arrangement of the display characters by deleting a selected character or a selected line of characters and leaving a blank space either at the end of the line or of the "page" in which the single character is deleted or leaving a blank character line at the end of the "page" in which the characters line is deleted. Additionally, means are provided for inserting a character and forming an additional character position at either the end of the line or the end of the page in which the character is inserted and for inserting a line of characters and deleting the last row from the display. The operation to effect the above changes is described in connection with logic circuitry (not shown) and in general consists of the controlled insertion of registers including "D" type flipflops in the recirculating paths between the registers RFL and REP or the controlled interruption of such paths to insert new data, including blank data, or to eliminate data to be deleted. When a complete line of data is to be inserted and the last line deleted the registers RFL are controllably duplicated the duplicate registers being set with the data for the line to be inserted (which may be blank data) which is introduced into the registers RFP whilst the normal retisters RFL hold and then eliminate the corresponding existing line of data after which the recirculating path reverts to normal. (For Figures see next page.)