GB1336597A - Video display systems - Google Patents

Abstract

1336597 Cathode-ray tube display FUJITSU Ltd 23 Oct 1970 [25 Oct 1969] 50571/70 Heading H4T An arrangement for displaying characters and also vertical bar graphs on a cathode-ray tube by selective bright-up during a raster-type scan comprises, in addition to a memory store for the incoming character codes and a character generator converting these codes into video bright-up signals, an arrangement for comparing codes representing the tops of bar graphs with the contents of a counter holding the current scan-line number and ordering bright-up signals when the scan-line number is greater. The data for display is received as a sequence of 7-bit groups in series-parallel mode, each group representing either (a) an alphanumeric character for display (top and bottom rows and lefthand column, Fig. 2) or (b) an indication that bar-graph data is to start or has ended (columns 2 and 8 of rows 2-5, Fig. 2), or (c) a bar graph height (columns 2-7 of rows 2-5). These 7-bit groups are held in circulating stores and transferred, a row at a time, to further circulating stores (buffers) where they are read out at 10 consecutive scan line times to control the display; this read-out is in parallel on lines T1- T7 (Fig. 4). A counter Reg 2 receiving scan-line signals ST counts up to ten (seven display lines and three inter-row lines) and provides on S1-S3 a binary-coded output of the scan-line numbers 1-7 which in conjunction with the character decoder D1 (recognizing characters for display) controls the generation from a magnetic core matrix read-only store PM of the bright-up signals for the seven successive scan lines (e.g. lines 11-18, Fig. 2). These signals; five bits for each character, are transferred in parallel to dynamicizer Reg 3 where they are read out by clock pulses CCT and passed (assuming #K=1) via AND gate A43 to the video amplifier VAMP. When a start-of-bargraph code is identified (e.g. row 2, column 2, in Fig. 2) in code detector DET, output K is switched to 1 to open A41 and close A43, and subsequent 7-bit codes representing the levels of the tops of the bar graphs in columns 3-7, Fig. 2, are compared in Reg 1 with the scan-line count and if the latter is equal or greater a signal of duration equal to five clock pulses is passed to A41 to generate five bright-up pulses for that column. At the same time the codes held in the buffers are caused to recirculate therein not only for the ten scan-line periods representing a character row but also for subsequent character rows while K is set. On receipt of an end-of-bar-graph signal (e.g. in column 8, Fig. 2) K, K return to 0, 1 for character display.