Patent GB-874807-A (GB)
Title: Electronic programme control equipment
IPC: G06F9/48
Filed: 1958-12-05
Abstract: 874,807. Input-output apparatus for calculators. STANDARD TELEPHONES & CABLES Ltd. Dec. 5, 1958 [Dec. 12, 1957], No. 39310/58. Class 106 (1). In a data processing system one central data-processing station ZVA is capable of connection by data-transmission lines i, Fig. 1, to a number of input-output units 1, 2 ... m, and there is at least one programme control line p from each unit, the programme of operations that is to be performed being controlled by a marking on one of these lines and the programme-line markings are delayed until the corresponding data transmission line has been connected to the central station and then serve through electronic switching means to select the desired programme. Each unit has an information transmission line i and a programme control line p. The former pass to a gating device D1 and the latter to a gating device D2 which connects the selected unit to mark one of n leads pe. A programme selector PW responds to the marked lead to select one of n different programmes. A connection S from the device D1 ensures that the markings are not applied to leads pe until the selected data lines i have been connected to the central station ZVA. The signals on the leads pe may be used also to indicate that the units 1, 2 &c. are ready to operate. Alternatively, there may be a separate call line from each unit adapted to control the selector devices D1 and D2. In Fig. 3 the input-output unit 3 has a data line i3, a call line r3 and a programme selector line p3 while unit 4 has lines i4, r4 and three programme lines p41, p42 and p43, one of which may be selected at the unit by a programme key. The device D1 which connects one of the data lines i1 i2, &c. to the central station, consists of a number of And gates Gi. The call lines r1 r2, &c. are connected to the line finder AS which contains a gate Gr for each call line. The outputs of these gates pass on leads S1, S2, &c. to the second inputs of gates Gi. The call lines are scanned cyclically by a counter Z the stages of which enable gates Gr in succession so that where a call signal is present a signal on the corresponding lead S1, S2, &c. enables the associated gate Gi to allow data from the calling unit 1, 2, 3, &c. to pass to the central station. The counter Z is supplied with pulses through a gate Ge which is closed whenever there is a signal on one of the leads S1, S2, &c. Scanning therefore stops when a call signal causes the associated gate Gr to provide an output. After the predetermined programme of operations has been carried out the call signal ceases and the counter continues to search for other call signals. In the device D2 there are And gates Gp, one for each programme line p1 p21, p22, p23 ... pm1, pm2. The gates are enabled in successive groups corresponding to the units 1, 2, &c. by connection to the successive counter stages. If unit 2 issues a call signal, gates corresponding to lines p21, p22 and p23 will be enabled when the counter reaches stage Z2. Assuming the unit 2 has marked line p22 a marking will be passed, say, to line pe3 to select programme 3. The alternative form is also described in detail, in which a signal on the appropriate programme control line also serves as a call signal.