Telephone exchange recognising various switching codes - uses interrogating device shared by selectors at indicating positions

摘要

The telephone exchange has an interrogating device recognising individual switching codes appearing at selectors at indicating positions and shared by the selectors. The interrogate divice has a store and a connecting device. The store's contents are read out and passed to the connecting device to interrogate the various indicating positions for the presence or absence of a switching code. The connecting device passes a voltage representing the store's contents to a voltage measuring device whose second input is connected via a switch to the indicating positions of the selectors.