In this article we describe the design of the HPSoC, a multi-channel waveform digitizing and processing Application Specific Integrated Circuit (ASIC) to readout fast and dense sensor arrays (e.g. LGADs). The chip will be able to service up to 100 channels, for bidimensional sensor arrays with a pitch of down to 300 um, operate with 10 GSa/s waveform digitization and use autonomous triggering, feature extraction and multichannel data fusion. In this paper, we present the architecture design, and the design and fabrication of a prototype with 4 channels to validate the components.