334 THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1953 



In preparation for a run all slips bearing initial time entries are stacked 

 in order of their times of origination. Slips for the second stage of a call 

 are kept in a separate stack. At the conclusion of a dial tone action when 

 the time of origination of the second stage is determined, the associated 

 call slip is located, the time is entered on this slip and it is inserted in 

 proper order in the stack of originating calls. In the case of re-originated 

 calls, the information from the old call slips is recopied on a new slip 

 mth the new time of origination and these slips are placed with waiting 

 calls in the proper time order. 



Detailed Description of Equipment and Functions of 

 THE Operating Positions 



THE originating POSITION 



The originating position, in relationship to the rest of the throwdown 

 machine, appears to the extreme right of Figs. 1 and 10. Detailed views 

 of the two wings of the position are shown on Figs. 16 and 17. The prin- 

 cipal features of this position are arrays of jacks and wooden pegs rep- 

 resenting subscriber lines and incoming trunks, together with associated 

 time counters and detectors. The chief function of the originating opera- 

 tor is to enter all calls into the system at appropriate times. This re- 

 quires that the stacks of call slips, visible in Figs. 16 and 17, be held at 

 this position. These call slips are arranged in order of their originating 

 times, with latest time on top, and carry the originating line identifica- 

 tion number so that line peg and call slip can be associated when the 

 call is to start. 



The line array, split into two wings, contains jacks and pegs for all 

 subscriber lines in the office. The jacks which are simply holes with no 

 electrical function, are arranged in a coordinate grid to assist in quick 

 location. Twenty frames are provided, each holding 500 lines for a total 

 of 10,000 lines. 



The array is divided into 20 horizontal sections, running across the 

 two wings, each representing a line link frame. Each frame is divided 

 vertically into 10 subgroups of 50 lines, each representing a horizontal 

 group. Since the directory number assigned to a subscriber line in a 

 crossbar office is purely arbitrary and has no physical significance, it is 

 not used in the present case for line identification. Rather, an equipment 

 number, which represents the location of the line on a line link frame, 

 is used. This is a five digit number, stamped on the peg, and made up 



