THE TWISTOR 



1323 



The third method of operating the twistor, mode C, is similar in 

 nature to a method proposed by J. A. Baldwin/ In this scheme the wire is 

 not twisted, so that neither screw sense is favorable. By the proper ap- 

 plication of external current pulses, information will be stored in the 

 wire in the form of a flux path of a right-hand screw sense for a "1", 

 and a left-hand screw sense for a "0". The operation of the cell is indi- 

 cated in Figure 6. Note that the writing procedure requires a coinci- 

 dence of currents; the reading procedure does not. The sign of the 

 output voltage indicates the stored information. 



Modes A and C are best suited for moderate sized memory arrays 

 since the readmg procedure is not a coincident type selection. Thus to 

 gain access to ri storage points, an access switch capable of selecting 

 one of n points is recjuired. For large arrays the use of mode B is mdi- 

 cated. It then becomes possible to select one of n points with a 2n posi- 

 tion access switch. The crossover point (about 10^ bits) is determined by 

 access circuitry considerations. 



WRITEx^ 



I I 

 I I 



^ 



2 



WRITE, 



^=C>' 



~L 



OR 



^ 



^^ 



c^ 



^ 



) 



I I 



^ 



SIGNAL OUT 



READ 0=Z] 



rT^ 



I I 



I I 



OR 



Fig. 6 — Read-write cycle for a twistor operated mode C. The wire is not 

 under torsion. 



