The computer used core memory for all storage, lacking "secondary" systems such as a memory drum. Normally the memory for a machine would be built up by stacking a number of core assemblies, or "planes", each one holding a single bit of the machine's word. For instance, with a 40-bit word as in the DRTE, the system would use 40 planes of core. Addresses would be looked up by translating each 10-bit address into an X and Y address in the planes; for 1,024 words in the DTRE this needed 32×32 planes.