GB1423170A - Character generator for generating coded signals - Google Patents

Abstract

1423170 Selective signalling SOC DE APPLICATIONS GENERALES D'ELECTRICITE ET DE MECANIQUE 6 Jan 1973 [6 Jan 1972] 60143/72 Heading G4H In a character generator, counters 11, 12 scan character addresses in a read-only character store 10 and counters 21, 22 scan bit addresses in a control bit store 20, 20<SP>1</SP>, a character being taken from store 10 when a bit a predetermined value is reached in the control bit store. To generate a single character, the counters 11, 12 and 21, 22 are incremented together, the character store 10 output being indicated as valid at CPR (Fig. 3A, bottom left) when a set bit is encountered in the control bit store 20, 201. One of 3 compartments 101-103 of store 10 is selected to be addressed to provide the character. A character can be generated repeatedly while a repeat signal RE (Fig. 3A, top left) is present, incrementing of 11, 12 being discontinued when the required position is reached but incrementing of 21, 22 continuing, with " valid " signal at CPR whenever equality with 11, 12 occurs as detected at comparators 31, 32, 50, until RE ends. A sequence of characters can be obtained in the presence of a signal SE (Fig. 3A, top left), the sequence being obtained from successive compartments 101-103 at a given address then successive compartments at the next address and so on. For this, the compartment selector 14 is incremented at the same rate as 21 and 22, whereas 11 and 12 are incremented at one third this rate, and a character of the sequence is obtained each time coincidence occurs at 31, 32, 50. A wait signal AW (Fig. 3B, bottom) can be generated.