The PS1 didn't really have a GPU in the modern sense. It had a rasterizer. That's it. A thing that draws triangles or quads, with primitive texturing. It doesn'

The PS1 didn't really have a GPU in the modern sense. It had a rasterizer. That's it. A thing that draws triangles or quads, with primitive texturing. It doesn't have any vertex processing. It doesn't even understand the Z dimension. Nothing even remotely resembling shaders, of course. At its core, all it does is draw 2D triangles and quads at integer pixel coordinates. Instead, the CPU had specific instructions (a coprocessor, in MIPS parlance) to accelerate fixed-point geometry processing. That's where the math happens. So it did have an "FPU" - a fixed-point unit, not a floating-point unit :-)