No. 1 ESS Scanner, Signal Distributor, and Central Pulse Distributor

T h e No. 1 electronic switching system (ESS) includes peripheral u n i t s which serve as buffers between t h e central control with its associated stores a n d the outside world of lines, t r u n k s , a u t o m a t i c message accounting (AMA) centers, a n d m a i n t e n a n c e personnel. T h e peripheral units include t h e switching network, scanners, signal distributors, central pulse distributors, A M A recording e q u i p m e n t , teletypewriters a n d miscellaneous common systems circuits. T h i s article describes t h e scanners, signal distributors a n d c e n t r a l pulse distributors. Associated articles describe t h e network 1 and other peripheral units 2 of No. 1 ESS. II. FUNCTIONS OK SCANNERS, SIGNAL DISTRIBUTORS, AND CENTRAL PULSE DISTRIBUTORS 2.1 Scanners E v e r y telephone switching system embodies some mechanism for detecting service requests a n d supervising calls in progress. I n p u t information of this n a t u r e is furnished to No. 1 E S S by t h e operation of scanners which sample or scan lines, t r u n k s a n d various diagnostic points at discrete intervals of t i m e as directed by t h e system. It m i g h t be said 2255