GB839245A - Improvements in or relating to electronic counters and electronic digital calculating equipment - Google Patents

Abstract

839,245. Electronic calculating-apparatus. INTERNATIONAL COMPUTERS & TABULATORS Ltd., Aug. 17, 1956 [Aug. 19, 1955], No. 23952/55. Class 106 (1). In a binary electronic calculating apparatus (described in Specification 839,241) control signals are produced by a counter which is fed with clock pulses from a magnetic drum, the counter being kept in step with the rotation of the magnetic drum by arranging that the output from the counter upon counting to a predetermined number blocks the input gate to the counter, there being a synchronizing pulse read from the drum at the end of each revolution which unblocks the input gate to the counter so that counting can begin on the next cycle of clock pulses. Part of the apparatus is shown in Fig. 1. The magnetic drum 2 has a number of reading-heads 1 for data storage tracks, a head 5 reading the clock pulses and head 7 reading the synchronization pulse. Sixteen trains of forty clock pulses are detected by head 5 for each drum revolution and are passed to the counter 23, 24 through input gate 22 which is controlled by trigger 26. The counter part 23 counts up to forty and gives an output pulse which is passed to counter part 24. Part 24 counts up to sixteen and then gives an output pulse which is passed to trigger 26 to set it and open input gate 22. In the space between the end of the last word and the beginning of the first word on the drum the synchronization pulse is passed from head 7 to unset trigger 26 and open the gate 22. The number registered in counter part 24 is used, by connections on line 36, to select the word to be read out from the drum.