Were there really significant similarities between the N64 and the PS2 architectures? My understanding is that all the "first generation 3D consoles" had substantial weaknesses in their architecture, due to lack of experience, which were ironed out in the next generation.
They weren't identical, but they sure stood apart from others. Both used 64-bit MIPS CPUs, both had dedicated 128-bit SIMD cores driving their display list based GPUs. For a 1996 N64 having a SSE2 level SIMD was absolutely amazing. They're even similar from emulation standpoint: only in the last decade we've got enough CPU power to consistently emulate them at full speed.
