Subway and its mysteries

[Gilloo]

I've noticed a strange thing with a Sandisk Cruzer 256Mo and Subway

On Windows, usb 2.0 hispeed bulk endpoints are 512 bytes long.
On Subway usb 1.x fullspeed bulk endpoints are 64 bytes long.

On Subway, there are 2KB memory for data. If I use only 64 bytes for a transfer, It's a bad thing, for what are done all the rest ? So I got a grazy idea: in a transaction batch, I've put 8 data transfer (each 64 bytes long) for the same bulk endpoint, in hope to get the same 512 transfer...
and...
it works!!! I get nearly 400KB/s with fat95 (with ANAIIS, on a simple 68000!).

but this tip fails on 4GB thumbs, so, I have some questions:

Is it safe or what can I must check before to try this *dangerous* mode ?
What is the maximum data transfer rate with Subway on a 68000 (is it 64KBytes/s (64 bytes per ms) or higher) ?

thanks.

[Gilloo]

Hi Michael

I forgot this link, sorry
http://www.e3b.de/usb/index_e.html

How does the transfer fail on the 4GB stick?

First packet is ok, second and other packets fail (with STALL)

I thinking that bulk data endpoints have the same behaviour than endpoint 0, one packet per usb frame, but in this condition it would be impossible to get rate upper than 64KB/s (64 B/ms) So there is certainly a tip to organize packets in the transaction, perhaps by interleaving with other packets... perhaps I'm wrong.

I try to speed up this part, because usb thumbs are better than disks.
Actually I must wait 5 minutes to mount 4GB thumbs (because fat95 reads 4Mo of data at mount time)

thanks.