The realization of a programmable metasurface, enabled by a custom application-specific integrated circuit (ASIC), is presented in this paper. The ASIC is used to provide an adaptive complex impedance load to each of the metasurface unit cells. Various technology nodes are analyzed for the implementation of tunable complex impedance loading elements before one is selected for the final implementation, in which four complex loads are placed within each integrated circuit, and each load is controlled by two digital-to-analog converters. Furthermore, the ASICs populate the back of the metasurface to form a mesh network to enable programmability. The paper includes practical limitations that affect the realization, as well as an example adaptive metasurface absorber that builds upon the practical tuning range of the ASIC. Perfect absorption for both transverse electric and transverse magnetic polarization is demonstrated.