A memory controller maintains a mapping of target ranges in system memory space interleaved two-ways across locations in a three-rank environment. For each range of the target ranges, the mapping comprises a two-way interleaving of the range across two ranks of the three-rank environment and offsets from base locations in the two ranks. At least one of the ranges has offsets that differ relative to each other. Such offsets allow the three ranks to be fully interleaved, two ways. An instruction to read data at a rank-agnostic location in the diverse-offset range causes the memory controller to map the rank-agnostic location to two interleaved locations offset different amounts from their respective base locations in their ranks. The controller may then affect the transfer of the data at the two interleaved locations.