Signaling rate, SPU and memory cards

[Missle Seeker]

Hi. Just want to make clear for myself couple details about Ps2's hardware.
Does anyone know signaling rate of iLink? I'm pretty sure that Sony wouldn't use max rate (which 400 Mbps (for 1394a)), so it's only one hundred. Am I right?
Er..Ofcourse I regret for asking this, but..."Jedi's gotta do, what jedi's gotta do..."
When I saw article from ARsTechnica about EE's architecture (I believe exact link exists in "sticky" in questions and answers) in their figures there is SPU2 near IOP. So...if there is #2 then somewhere must be SPU1. Or it's functions are given to VU1 (among with emulation of Dolby Digital)? And what are those SPU's? I mean, can some mighty and respectable corp. (like Yamaha) manufacture them?
On "coup de grace" final question: what is exact transfer rate of standart Ps2's Memory Card? (Exclude that it's "almost 250 times faster then cards from Playstation 1)
Thank you for your attention

[mrbrown]

i.Link is S400 or 400Mbps.

SPU2 is a single audio chip with 2 "cores" each having 24 voices. It's called SPU2 because the original Playstation's audio chip was called the SPU. There is no connection between SPU2 and the vector units. The SPU2 was developed in-house by Sony.

[Guest]

Ilink defaults to 400Mbs, but a game/app can choose 200Mbs or 100Mbs. Even when 400Mbs is used, its no big deal because most games (the few) that use it aren't doing heavy streaming of data.

Not much public data exists on the hardware underpinnings of the pad/memcard ports.

Pads and Memcards are ultimately driven from a serial port. Most embedded serial ports are capable of anywhere from 256Kbs to 1Mbs. I don't know the particulars of the one on the PS2.

I believe a framed data stream is used to divide access between the various cards and pads, so it may be that throughput to a particular memcard would be a fraction of the total stream throughput.

But this is all speculation on my part.