Interconnections for modular die designs

Interconnections for modular die designs are disclosed. In one aspect, a die that is a chiplet is designed and tested for suitability. After approval of the chiplet design, multiple dies or chiplets may be coupled together within a multi-die package to form a package having desired computing capabilities. After assembly, each chiplet is provided a unique identifier, such as by setting a fuse. Based on the unique identifier, each chiplet is made aware of how interfaces to other chiplets are configured so that signals may be routed appropriately. Using modular chiplets in this fashion reduces testing requirements and non-recurring expenses while increasing flexibility for design options.