Multiple active vertically aligned cores for three-dimensional chip stack

A method for operating an integrated circuit (IC) stack device, the method comprising:

• enabling, on a first side of a primary IC, a set of first enabled cores;
• disabling, on the first side of the primary IC, a set of first disabled cores;
• enabling, on a first side of a secondary IC, a set of second enabled cores;
• disabling, on the first side of the secondary IC, a set of second disabled cores having more cores than the set of first disabled cores,
• adding a peripheral component connection to a location on the IC stack device such that the secondary IC is between the peripheral component connection and the primary IC, the peripheral component connection designed to electrically connect the IC stack device to one or more devices external to the IC stack device;
• and
• selecting a mode for control logic that is designed to:
• route, in a primary mode, signals from a particular enabled core of the first enabled cores to a data bus located within the IC stack device,
• route, in a secondary mode, signals from a particular enabled core of the second enabled cores to a data bus located within the IC stack device, and
• route, in a dual mode, signals from both of the particular enabled cores to a data bus located within the IC stack device.