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THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1952 



and C relays. In the following tabulation the combinations below the 

 horizontal line are inconsequential. 



B C D E 



(B + D + E) 



The expression becomes: 



(C + E' + B'D'){C' + D' + BE){B + D + E) 



[£; + (C + 1 + B'D'){C' + D' + BO){B + /) + 0)] 



[^' + (C + + B'D'){C' + JD' + B1)(B + Z) + 1)] 



(14b on E) 



[E + (C + D')(B + D)W + (C + B'D')iC' + D' + B)] 



(9a, 9b, 10a, 10b) 



[E + (C + D')(B + D)][E' + CD' + C^ + 5'Z)'] (8b, 9a, 4b, 5a) 



[E + (C + jD')(5 + i))][A^' + BC + 5'Z>'] (12b) 



[E + (C + i)')(5 + D)][E' + (5 + Z)')(B' + C)] (13) 



Fig. 4d shows the schematic of the above expression. It is possible to 

 put this in a bridge form without other changes because of the manner 

 in which the front and back contacts of D are related to the other con- 

 tacts. Comparison of all the circuits of Fig. 4 indicates that they all use 

 the same number of contacts although final decision should be post- 

 poned until all the output circuits are obtained and the ease of combina- 

 tion of the different circuits can be compared. 



The procedure for determining the remaining code leads is carried out 

 on the following pages. 



