MAGNETIC DRUM TRANSLATOR FOR TOLL SWITCHING OFFICES 745 



sumption, but since transistors are essentially current-operated devices 

 t hey would seem to be particularly suitable for working with microsecond 

 [)ulses in the environment of existing relay-equipped offices where the 

 majority of interference transients are capacitively-propagated voltage- 

 tlisturbances. 



Evaluation of the magnetic drum reveals it to be a safe and vevy roli- 

 ;il)le means of storing several hundred thousand bits of information. Dur- 

 ing the course of these tests, the drum functioned perfectly, and the trans- 

 lations that were recorded at the beginning of the test were retained until 

 near the end, when they were deliberately altered. During this interval 

 of nearly continuous operation there was no detectable deterioration, or 

 iliange in the signals obtained from the drum. 



The results obtained from the tests of this particular drum translator 



indicate that the associated circuitry, working with microsecond pulses, 



ran be designed to measure up to the exacting standards demanded for 



i telephone office apparatus, whether the application be that of a magnetic 



(hum translator or some other type of equipment. 



i;eferences 



1. W. D. Lewis, Electronic Computers and Telephone Switching, Proc. I.R.E., 



41, pp. 1242-1244; Oct., 1953. 

 '2. W. A. Malthaner and H. E. Vaughan, An Automatic Telephone System Em- 

 ploying Magnetic Drum Memory, Proc. I.R.E., 41, pp. 1341-1347; Oct., 1953. 

 '■\. .J. H. McGuigan, Combined Reading and Writing on a Magnetic Drum, Proc. 



I.R.E., 41, pp. 1438-1444; Oct., 1953. 

 4. L. N. Hampton and J. B. Newsom, The Card Translator for Nationwide Dial- 

 ing, B. S. T. J., 32, pp. 1037-1098; Sept., 1953. 



