GB1487855A - Data handling arrangement - Google Patents

Abstract

1487855 Selective signalling GENERAL ELECTRIC CO 15 Nov 1974 [26 Dec 1973] 49550/74 Heading G4H In data handling apparatus, a data source intermittently delivers data groups at different speeds and in occasional overlapping relationship via gate apparatus to a data register, a monitor circuit opening the gating apparatus in response to the presence of overlapping data groups in the register and closing it in the presence of a valid, single data group in the register. In a keyboard unit, actuation of a key at 1 is encoded 5 and passed by gates 6 at an input register 7. If one and only one key is actuated, detectors 11, 12 cease to enable gates 6 via OR 13 and enable AND 19 to pass the next timing pulse 36 from a printer 25 to gate at 8 register 7 to an intermediate register 15, and after a delay of one timing pulse 36 at 21 to produce a pulse from OR 13 which resets register 7 via AND 28 and opens gates 6 for the next keyed character. Presence of a character in register 15 is detected 16 to produce a pulse to printer 25 and set a flip-flop 48 so that the next timing pulse 36 transfers 37 (with addition of start, stop and parity bits) the output of intermediate register 15 (after possible alteration at 35) into a shift register 40 which converts from parallel to serial. The printer 25 provides pulses 42 to sample 43 the data bits into a bit buffer 44 to feed the printer 25. Rollover problems are avoided since the period of timing pulses 36 is less than the interval between successive key actuations during rollover typing.