Miniature Memory Planes for Extreme Environmental Conditions

Abstract

Two serious limitations of present memory systems by using ferrite cores have been their relative bulk and narrow operating temperature range. A marked reduction in size has been achieved by use of a “continuous wire” method of inserting drive lines through memory planes and then folding the planes. This method eliminates the conventional frames and all solder connections between planes. By greatly reducing the number of solder connections, the new method increases reliability and facilitates assembly of stacked memory planes. A typical folded stack of memory planes occupies as little as 2% of the volume of its conventional counterpart. The new miniature memory stacks perform as well as conventional units. The development of ferrite memory cores operable at ambients as high as 85°C, 100°C, and 125°C (together with the greatly reduced volume of the memory stack) allows operation under extreme environmental conditions with a minimum of space and power requirements. The folded memory planes are packaged with a heating element and control circuit which maintain the temperature of the cores at the maximum ambient. A tested prototype of twelve (12) 16×16 memory planes, along with the heating element and control circuit, measures 2 in.×212 in.×212 in. and has been successfully operated in the temperature range -55°to +125°C. Ferrite cores have been perfected of both the “fast” relatively high drive and relatively “slow” lower drive type. They are Mg-Mn ferrites with possible minor additions of other bivalent oxides.