We propose a path to achieve an ambitious target that has never been tried before: a terabyte of on-chip memory for petabit/second of bandwidth with < 5W of power. Conventional methodology of on-chip memory design is bottom up where the choice of bitcell topology and associated peripherals are predetermined. The resulting memory is sub-optimal and often suffers from high power and poor bandwidth. We approach this problem from top down where the capacity, bandwidth and power specifications guide the choice of bitcell. Our evaluation shows that domain wall memory (DWM) can be a potential technology that can meet TB capacity and Pb/s bandwidth with shoestring power budget. Categories and Subject Descriptors B.7.1Types & Design Styles - Advanced Technologies General Terms Performance, Design.