structure has both isolation devices and equilibration devices fig1 is a mask layout for a circuit embodiment in which the twist structure has isolation devices but no equilibration devices each of these mask layouts are broken down into three detail masks fig1 14 and 16 correspond to fig1 while fig1 15 and 17 correspond to fig1 as explained below with diffusion areas shown in fig1 and 17 first metallization level metal 1 in fig1 and 15 and polysilicon layout in fig1 and 13 contacts are shown on each level so that the drawings can be matched up note that fig1 is a layout of the circuit shown in fig7 except that four twisted bit line sets are shown in the current drawings subarrays a and b are shown at the top and bottom of the layouts while the central area shows details of the isolation and equilibration devices as well as the bit line twists fig1 and 17 respectively show the diffusion regions b bl when equilibration devices are used and when no equilibration devices are desired in fig1 diffusion region d 0 for example will carry a portion of bit line bl 0a and a portion of bit line bl 0b separation of the two digit lines is accomplished by a transistor whose gate is.