Patent GB-1331837-A (GB)
Title: Data display
IPC: G06F3/153
Filed: 1971-03-31
Abstract: 1331837 Cathode-ray tube displays INTERNATIONAL COMPUTERS Ltd 31 March 1971 8759/71 Heading H4T In a data display, a process or unit 10 is connected to standard interfaces 13, 14 for data and command signals to TV displays 15, 16. The display signals are core stored in unit 10, and the input/output system is shared for the A and B channels in alternate successive cyclic time intervals. Plural data lines 20, 30 and command lines 21, 31 extend from the interface to temporary triple flip-flops command stores 22, 32 whose output lines 23a, 23b, 23c; 33a, 33b, 33c communicate with paired AND gates 70 to 75 whose outputs excite OR gates 76, 77, 78. Data lines 20, 30 are alternately connectible over gates 42, 43, 44, 45 to buffer store 41 of a bit serializer containing shift register 46, whose serialized output is gated alternately over 49 or 50 as video inputs to TV display units 15 or 16 whose line and frame syncs are derived simultaneously from control 55. A timing circuit comprises bi-stable 56 switched at half frame speed from control 55 to alternately enable AND gates 49, 50 in complement and also to alternately enable AND gates 42, 43, which transmit data from multiple lines 20, 30 of channels A, B over OR gate 44 to AND gate 45, which when enabled from logic control 64 transmits data to multiple line 40. It also provides shift signals ,for register 46. Buffer store 41 is alternately energized from data lines 20, 30 while commands from lines 21, 31 are continuously available to stores 22, 32; so that a proximate command for data on one channel is stored during the display period of the other channel. AND gates 70 to 75 are paired to excite OR gates 76, 77, 78 and gates 70, 71 are energized as to one input from stores 22, 62 respectively and as to the other from the antiphased complementary outputs of bi-stable 56. The gates 72, 73, 74, 75 are similarly energized in association with channels A, B. Thus gates 70, 72, 74 and gates 71, 73, 75 are respectively enabled together; and OR gates 76, 77, 78 supply c, b, and a command signal of channels A, B on successive alternate cycles of the displays to control logic 64, so as to control the performance of a particular operation, or to constitute a binary word which with a decoder may specify further functions. At least one such command signal initiates display of data by enabling gates within the logic 64 to apply shaft pulses to register 46 and data passage enabling pulses to gate 45. Register 46 is connected to clock line 85 during scanning period, and the logic 64 is enabled in response to the half frame speed signal on output 86 of sync control 55, which overcomes the normal flyback inhibition of gating between clock line 85 and register 46. The clock frequency is subdivided to pulse gate 45 at frequency suitable for data transference to buffer 41 with a capacity of 1 or 2 words of 24 bits. Other command signals control alternative functions at a local display terminal, which may have a keyboard for feedback of information over lines (not shown) to a computer enabled by the control logic 64. Data transmission is locked on keyboard operation until arrival of a positive unlock command also instructing display of next available data. The clock is crystal controlled to drive control logic 64 and sync control 55, which incorporates a subdividing counter.