356 



THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1953 



It should be emphasized again that the principal function of a throw- 

 down machine is to provide data, under controlled conditions, which 

 can be used to develop and check a comprehensive theory of operation 

 of a complex system. A secondary function is to study the reaction of 

 the system to specific equipment or circuit arrangements. The No. 5 

 throwdown machine has been used for both purposes. All runs have 

 furnished masses of statistical data which have been very useful in 

 formulating traffic theories applicable to No. 5 crossbar. Some data, 

 such as those on link matching, have a more general field of application. 



All throwdown runs have emploj^ed a basic size office of twenty line 

 Unk frames and ten trunk link frames, loaded by 9000 subscribers. On 

 the first two runs, a traffic level designed to load these frames to their 

 normal capacity was applied to the machine. This level can be called 



Table III 



