The DSP3 Multiprocessor Project at AT&T Bell Laboratories, sponsored by the Defense Advanced Research Projects Agency (DARPA), has produced a multi-GFLOP (10(9) FLoating Point OPerations per second) machine that is applicable to a variety of signal processing and pattern recognition problems. A companion DARPA sponsored program, the Ultra-Dense Project, is utilizing silicon-on-silicon multichip module (MCM) technology and innovative advanced packaging and physical design to achieve a parallel three-dimensional (3-D) digital signal processor based on the DSP3. This paper presents an overview and outlines systems architecture, Micro-Inter-connect Technology (Si-on-Si MCM), and unique innovative advances in physical design and packaging technology leading to an Ultra-Dense project demonstration.