GB1371789A - Display apparatus - Google Patents

Abstract

1371789 Cathode-ray tube displays WESTINGHOUSE BRAKE & SIGNAL CO Ltd 25 Nov 1971 [22 Dec 1970] 60708/70 Heading H4T Train describer display apparatus comprises 56 cathode-ray display tubes CRT 1-CRT 56 (Fig. 1) in four groups SRA, SRB, SRC, SRD each of fourteen tubes on the screens of which alpha-numeric data consisting of four adjacent characters (Fig. 2) are produced in a 7 x 5 dot matrix format by bright-up of the tube beams during successive up and down scan of a vertical line roster. The beam control character data for each tube is derived from a respective 150 bit recirculating shift register SR1, SR2-SR14 &c. and comprises 140 character data bits (= 4 Î 7 Î 5) the remaining 10 bits allowing time for the scan fly-back. The shift registers SR1-SR14 &c. may be updated under the control of a display access module DAM including an address register AR specifying the particular group SRA-SRD which contains the shift register of the display to be up-dated and an input register IR specifying the particular one of the latter by an output X1,X2-X14. The address register AR is fed from an address decoder AD supplied over an address highway AH and the input register IR is fed from a data highway DA which in addition to the X1,X2-X14 data also receives the up-dating character modifying data. The latter data is then fed to a modification word register MWR and in response to a signal from the time base TB the recycling path of the selected shift register is interrupted by gate means (not shown) for the duration of a scan and the data in register MWR is transferred serially to the selected shift register. At the end of the scan the recycling path is closed and the new display is produced. Receipt of an address by decoder AD and of a correct parity output from parity check module PCM provides an output via gate G2 which gates the date into input register IR and also provides a "data accepted" signal back to the computer &c. which controls the display.