Just to make sure, I read that the CPU reads from the RSX at 16 megabytes / sec?

I can't recall exactly but that sounds right. It was exceptionally slow.

That’s why getting DMA right mattered so much.

I'm not quite sure what this means? DMA is the only mechanism that the SPUs had to access memory outside of their local store; it wasn't a matter of getting it right or wrong. Reading RSX memory by SPU DMA wasn't any faster than reading it from the PPU.

I’m sorry I thought you meant the CPU not the GPU.

I didn’t realize DMA didn’t help with GPU memory.