Twistor memory

Abstract: Line and trunk translation data and operating programs for no. 1 ESS are stored in a large semipermanent memory. This memory is provided by modular units known as program stores. Each program store provides 5.8 million bits of randomly accessible permanent magnet twistor memory organized into 131,072 parallel words. The information is stored in the state of small magnets affixed to aluminum cards. Each card contains 64 forty-four-bit words. Each store is designed to operate over a duplicated common bus system for both normal and diagnostic operations. The stores have a cycle time of 5.5 μsec. Such stores are an attractive and economical solution to the problem of providing large storage capacity for information which must be protected against accidental change. To provide an efficient and routine method for updating the information content of such stores, offices are provided with card writing equipment. This includes both card handling equipment and card magnetizing equipment under system control.

Abstract: The Piggyback Twistor (PBT) is an electronically writeable nondestructive-readout memory that has been built and tested in sizes up to 300,000 bits. The storage and sense functions are performed by thin magnetic tapes spirally wrapped in coincidence on a copper wire. The mode of operation is by linear selection using a ferrite core array for word access. “Ones” and “zeros” are of opposite polarity at the output terminals to ease the discrimination problem. This paper discusses details of the construction and operation of a piggyback memory. The magnetic properties of the two tapes are considered, and the theoretical read and write field limits are then examined. The the results are given for a 4,096-word 54-bit memory.

Abstract: A card changeable permanent magnet twistor memory element of improved characteristics has been designed. The desired characteristics were obtained by: (1) Halving the solenoid width to enhance the drive field. (2) Replacing the copper return wire in the twistor pair with a reverse wrapped twistor wire. (3) Installing a Permalloy sheet between the word solenoid and the solenoid board to reduce interaction fields within the memory. (4) Annealing the twistor wire to lower the coercive force and to increase the squareness ratio of the moly-Permalloy tape.

Abstract: The card-changeable permanent-magnet-twistor memory is a large capacity (ca 105 bits) storage media for information that is infrequently changed. The information is stored in the form of small bar magnets bonded to a removable plastic card. The magnets, when magnetized, inhibit the switching of a section of twistor wire at a twistor-wire-solenoid crosspoint. For maximum information density the magnet shape and strength must be optimized with respect to the magnet's action on the inhibited crosspoint and the fringing action on neighboring crosspoints. The objective is a magnet with a small dipole moment, but with adequate inhibition of the twistor switching over a reasonable range of misposition. Suitable magnet shapes and a general discussion of the stray fields in a large array of magnets are given. For maximum capacity, the transmission characteristics of the twistor wire and the character of the access switch must be considered. Two novel structures of this memory permit increased information density and capacity. The feasibility of a random-access high-density memory submodule containing 360,000 bits in 0.7 foot3 with a cycle time of 5 ?sec has been demonstrated.