System design parameters for electronic automatic exchange

IN DESIGNING the No. 1 Electronic Automatic Exchange (E-A-X^∗), Automatic Electric Laboratories tried to anticipate requirements for many years to come with a system that would be flexible enough to accommodate smoothly any new services that might be required. Experience had shown that such a system would necessarily have many elements of common control. As the nationwide telephone system becomes one large direct distance dialing (DDD) network and more and more calls are handled on an extended area service (EAS) basis, it requires sophisticated equipment (registers, translators, senders) to convert subscriber-dialed digits into switching instructions. If such facilities for storage and translation were provided electronically, it would be relatively easy and inexpensive to employ them for special services that might not be economically practical with present-day equipment. Such special services therefore became another objective of this development.