An integrated circuit package is disclosed that includes a first-pitch die and a second-pitch die. The second-pitch die interconnects to the second-pitch substrate through second-pitch substrates. The first-pitch die interconnects through first-pitch interconnects to an interposer adapter. The pitch of the first-pitch interconnects is too fine for the second-pitch substrate. But the interposer adapter interconnects through second-pitch interconnects to the second-pitch substrate and includes through substrate vias so that I/O signaling between the first-pitch die and the second-pitch die can be conducted through the second-pitch substrate and through the through substrate vias in the interposer adapter.