A Myriabit Magnetic-Core Matrix Memory

A coincident-current magnetic-core matrix memory was built giving random access to any of 10,000 bits in a few μsec. The memory cores, of a diameter less than 1/16″, are made on an automatic press from especially synthesized magnetic ceramic material with rectangular hysteresis loop. Automatic test techniques permit rapid sorting to insure uniformity of the magnetic properties of the cores. The memory array is driven by two ten-by-ten dc biased magnetic switches which reduce the number of address-selecting access vacuum tube drivers to 40 and the required driving current to the order of a few hundred milliamperes. The read-out signal originating from a winding linking all 10,000 cores is freed from the disturbing contributions of partially excited cores on the selected lines by integration over a period of time in which these cores are subject to equal and opposite magnetizing forces. The principles and techniques evolved for this experimental model demonstrate the practicability of an extremely reliable fast random access memory with a capacity of hundreds of thousands of bits, ushering in a new era in storage devices for information handling systems.