Abstract: A battery-powered computing system (20) including video decoding capability, particularly as pertinent to the H.263 standard, is disclosed. The system (20) includes a main integrated circuit (30) having an on-chip central processing unit (CPU) (32) and on-chip shared memory (33) for the temporary buffering of video image data that is retrieved and generated during the video decoding process. The CPU (32) is programmed to perform a combined P and B prediction process (46) upon a previously predicted P frame (P.sub.T-1), with accesses to internal buffers in shared memory (33) instead of to main memory (40). Preferably, inverse transform processes (48, 52) also access shared memory (33) rather than main memory (40). The combined P and B prediction process (46) preferably handles unrestricted motion vectors using edge pixels (P.sub.