GB1243886A - An improved multiplexer - Google Patents

Abstract

1,243,886. Distributers. NORTH AMERICAN ROCKWELL CORP. 25 July, 1969 [7 Aug., 1968], No. 37603/69. Heading H4P. A multiplexer which has two groups of input terminals 0-7, 8-15 and two output terminals 28, 29 is operable in two modes. In one mode (mode 1), the input signals on terminals 0-7 are passed successively to terminal 28 and then those on 8-15 successively to terminal 29, and in the other mode (mode 2) signals on one terminal in both groups are simultaneously passed to their respective output terminals, followed by other pairs of signals in succession. Clock pulses at terminal 17 step a binary counter comprising bi-stables 30, 40, 60, 70 whose first three stages feed a gating circuit 50. The last stage feeds a circuit 90 which, dependent on the mode selection signal at terminal 36, generates signals X, Y successively (mode 1) or simultaneously (mode 2). The gating circuit 50 receives #X, #Y and generates signals on its outputs a-p which control the multiplexing of the signals in the selected mode. Lamps 38 indicate the state of the counter, and a signal appears at 49 at the end of a scanning cycle. If an enabling signal (logic 1) is not present at terminal 35, or if there is a clear/reset signal at terminal 19, a circuit 100 resets the counter to zero. The counter can be set to a selected count, after being reset to zero, by a Read signal at terminal 18. The counter is then set to a count determined by signals on the counter terminals SET Q1-SET Q4, counting continuing from this point when the Read signal ceases.