GB1326103A - Data display system - Google Patents

Abstract

1326103 Cathode-ray tube displays INTERNATIONAL BUSINESS MACHINES CORP 16 Nov 1970 [21 Nov 1969(3)] 54355/70 Heading H4T A CRT display arrangement for alphanumeric data employs a multiplexing arrangement for storing character signals for the different displays of a number of CRT's. Data in the form of 6-bit bytes each representing a character is received on line 206 and transferred in parallel into four delay-line buffer elements 312, &c., each element holding 64 characters corresponding to a row of a CRT display and handling data for eight of the thirty-two independent displays, since when the data for one display is shifted down to the next line buffer it is replaced by data for the next display of the eight. Five buffers are provided, allowing the characters to be decoded five times into video bright-up signals for five lines of one of two interlaced fields, the display being a 10 Î 8 brightened dot matrix with a six-line space between rows of characters. Thus from any given line-buffer element an output is obtained which successively represents the 64 characters to be displayed on eight different display units, the output being 6 bits in parallel for each character in series. The rasters of the eight different display units in a group are started at staggered times, as each starts to receive its set of 64 characters for a given row at successive line periods. After all 32 first rows of characters have been supplied to 310 the second rows are supplied similarly and this is repeated for the whole display of 10 rows of characters, subsequent alternate repetitions relating to alternate interlaced fields. The outputs from the line stores are supplied to character generators PCG 1-5 which also receive a field signal and generate the appropriate bright-up signals for each line of the video display, namely eight bits supplied in parallel and dynamicized in a multiplex video generator. The dynamicized outputs from the five generators are made available to all display CRT's, which also receive linecount signals used to demultiplex and gate the appropriate output for bright-up. Schematic circuits for the functional units are described and illustrated, and the modifications necessary to allow display of lower-case letters (extending below the 10 scan lines of upper case), and display in colour are described.