AUTOMATIC TOLL SWITCIIIXr, SYSTEMS S7 1 



at TCs not 0(iuippe(l to send MF and in sonic cases from dialinj; A 

 boards in the local area of the C'SP itseli". 



Aside from the type of pulses received the functions of the two sendeis 

 are identical. They have a capacity for receiving and sending eleven 

 digits. They must register arbitrary digits given them by the decoder 

 and send them out as directed. They will send out digits by cither the 

 DP or the MF method as reciuired to control switches in distant offices, 

 and in some installations will also send digits to an outgoing sender in 

 the same office by the dr key pulsing method, which employs direct 

 current in xarious coml)ina1ions of \alue atid j)oIarity through a pair of 

 conductors. 



When the CSP is in a panel-crossbar area a group of outgoing senders 

 is pi'ovided to transmit either the type of pulses re(iuired by the eciuip- 

 ment in local panel offices or the type used to reach manual offices. 



3. MarLrrs 



The marker has been stripped of its usual translating functions and 

 performs most of its duties on instructions from the decoder. It is told 

 what leads to test for idle circuits and where they are to be found in the 

 trunk block connector, but having found an idle circuit it carries on the 

 process of setting up the coiniection independently of the decoder. 

 Having contact with both the incoming and outgoing trunks through 

 connecting circuits, it determines what frames they are located on, con- 

 nects itself to those frames, selects a path through them and sets up the 

 connection. 



In a single-train office one group of markers common to the office is 

 provided. In a two-train office there is a group of markers associated 

 with each train of switches. 



A single group of decoders serxcs the entire office whether one or two 

 trains of switches are provided. An impoi'tant element of the decoder 

 is the translator which will be discussed separately. 



The decoder contains several hundr(>(l r(>lays. A large gi'oup is used for 

 registering the information furnished by the translator. Others use this 

 infoi'mation to control the action of the markers and senders. 



One group of decoder relays which is of particular interest is the array 

 used for automatic selection of alternate routes. It is composed chiefly 

 of one relay for each C'SP to which the office has a direct grouj) of toll 

 lines. The relays are arranged in an orderly pattern sinudating the 



