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Fra en debat på comp.sys.mac.advocacy:

(engelsk)


I don't think that USB is daisy-chainable except through a port. Ports
are said to be "cascadable", not daisy-chained, and 4 cascaded USB 2.0
ports seems to be the limit. In fact, the spec warns that some USB
devices might not work after going through just two ports. Ports are
needed because USB is not self-arbitrating and relies on the port to
re-calculate the end of the uframe for each transaction. Because of the
delay built-in to the port chip protocols between arbitrations, the more
ports one has, the slower the USB interface as these delays build up.
OTOH, Firewire is self arbitrating and Firewire devices CAN be connected
together in true daisy-chain configuration and up to 63 devices can be
connected in this manner as long as the total cable length doesn't
exceed a total length of 72 meters with 4.5 meters between devices.
Firewire can use repeaters to extend this range and number of attached
devices as well. Also Firewire is isochronous data which guarantees
speed irrespective of load and supports multiple hosts on the same
network (which USB CAN ALSO do with a special chipset, but those are as
rare as hen's teeth!).

George Graves



--
regards, Peter B. Perlsø - liberterran.org, siad.dk
"The politicians don't just want your money. They want your soul. They
want you to be worn down by taxes until you are dependent and helpless."
- James Dale Davidson, National Taxpayers Union