Hierarchical six-transistor SRAM

An embodiment of the present invention is an SRAM memory array comprising memory cells with each cell containing six devices, the storage nodes which store the true and complement of the data are constructed from a four device, cross coupled flip-flop cell, wherein one internal storage node of this cell is connected through an access pass gate to one local bit line (LBL), the second internal storage node connected in a like manner to a second LBL, each LBL connected to a limited number, e.g. 8 to 32 of other similar storage cells, the two LBLs each connected to the gate of a separate read head nFET for discharging to ground one of two previously precharged global read lines so as to pass the inverse of the signal on the LBL and thus on the read head gate to a global read/write bit line.