This was pretty standard at the time - everything had a programmable DMA controller, which was capable of extensive data transforms, and often there had been so

This was pretty standard at the time - everything had a programmable DMA controller, which was capable of extensive data transforms, and often there had been some vector ALU stuffed in. The difference with modern arcs is that it was sitting in front of fixed function hardware. After you did whatever you wanted with the data it still went into the fixed function hardware and came out as pixels on the screen. You could have the same data pre-computed and fed to the GPU for the same result. In modern architecture, there are programmable ALUs inside the fixed function hardware and its fixed functions are very limited, it's just triangle setup and color/depth buffer, usually. The GPU input is just a list of indices, which is transformed by the programmable processors inside.