TRANSLATORS AND IDENTIFIERS IN SWITCHING SYSTEMS 



597 



the units leads to ten output code leads one of which will then be grounded. 

 By adding suitable relays this translator can be expanded to a system in 

 which the output code is a mark on one of a thousand or ten thousand leads. 

 The arrangement of Fig. 3 occurs frequently as a selection device and 

 when so used in the Bell System is now called a "relay tree".' It is often an 

 element of other types of translators. 



TENS 

 RELAY 



(1) 



GENERAL SYMBOL 



TENS 



i-; 



UK 



^r 



TO TENS 

 — > RELAYS 

 (3)-(9) 



::i TO 



> CONTACT 

 MULTIPLE 



8 OTHER 

 LEADS 



TENS 

 RELAY 



(2) 



^; 



Hli^L 



8 OTHER 

 LEADS 



7 OTHER 

 TENS RELAYS 



TENS 



RELAY 



(0) 



20 



70 

 OTHER 

 LEADS 



y> 



iUKi 



8 OTHER 

 LEADS 



100 



Fig. 3 — Fixed, systematic translator for changing a 2-digit decimal number to a cente s 

 imal base. (Changes "language") 



A 100-point step-by-step switch can, of course, be used as the equivalent 

 of the foregoing type of translator, and is frequently so used. In this case 

 the input code is two sets of decimal pulses to drive the selector to the 

 required point, and the output code is again a mark on one out of one 

 hundred output code marking leads connected to the bank terminals.* Such 

 a switch is also used in place of a relay tree as a selecting element in other 

 types of translators. 



* S. H. Washburn, "Relay Trees" and Symmetric Circuits, A.I.E.E. Transactions, 

 Vol. 68, 1949. 



* This is an elementary sample of a translator with sequential input and combinational 

 output. 



