THROWDOWN MACHINE FOR TRAFFIC STUDIES 307 



CHARACTERISTICS OF SUBSCRIBERS AFFECTING DATA 



Since the purpose of the throwdown machine is to evaluate per- 

 formance and traffic capacity of a simulated switching system under 

 conditions met in service, subscriber data fed into the machine must 

 represent, as nearly as possible, the characteristic actions of real sub- 

 scribers. Fortunately, telephone subscriber characteristics can be studied 

 in working switching systems which are similar to the one under throw- 

 do^\^l evaluation. Little error is introduced by such subscriber data 



TIME 



I POSSIBLE DELAYS 



CONTROL FUNCTIONS AND DIFFICULTIES 



REGISTER SEIZES MARKER CONNECTOR X DELAY FOR MARKER CONNECTOR 



I DELAY FOR MARKER (INCLUDES 



MARKER CONNECTOR CONNECTS TO MARKER X DELAY TILL CONNECTOR ACHIEVES 



I PREFERRED POSITION IN GATE) 



MARKER RECORDS TERMINATING NUMBER X 



AND LOCATION OF ORIGINATING LINE ^ 



MARKER TRANSLATES OFFICE CODE ^X 



MARKER HUNTS FOR IDLE TRUNK LINK i ^ All TR1IMK<? R1i<;y 



FRAME WITH IDLE TRUNKS X-*ALL TRUNKS BUSY 



MARKER SEIZES CHOSEN TRUNK LINK FRAME X TRUNK LINK FRAME DELAY 



MARKER LOCATES IDLE TRUNK X 



MARKER SEIZES NUMBER GROUP X NUMBER GROUP DELAY 



MARKER RECORDS TERMINATING ^Jl 



LINE LOCATION ^ 



MARKER SEIZES TERMINATING LINE LINK FRAME--X LINE LINK FRAME DELAY 



MARKER TESTS LINE FOR BUSY ^X-* LINE BUSY 



MARKER CONNECTS TO LINKS AND JUNCTORS I ^ ^uammc, K^icMATru 

 AND MATCHES CHANNEL -^-* CHANNEL MISMATCH 



MARKER OPERATES CROSSPOINTS X 



MARKER RELEASES TERMINATING LINE LINK FRAME-X 



MARKER SEIZES ORIGINATING LINE LINK FRAME X LINE LINK FRAME DELAY 



MARKER CONNECTS TO LINKS AND JUNCTORS X u. ^uammc. ii,c»-iAT,-u 

 AND MATCHES CHANNEL —X- * CHANNEL MISMATCH 



MARKER DROPS CONNECTION BETWEEN X 



REGISTER AND ORIGINATING LINE ^ 



MARKER OPERATES CROSSPOINTS X 



MARKER RELEASES REGISTER, TRUNK LINK X 



FRAME AND ORIGINATING LINE LINK FRAME jT 



MARKER RESTORES TO NORMAL X 



* MARKER MUST TAKE ALTERNATIVE ACTION 

 IF IT ENCOUNTERS THIS CONDITION 



Fig. 4 — Establishing an intraoffice call. 



