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USBASPI 2.27x tests (Announce)

posted by Doug E-mail, 09.01.2011, 18:20

One more thing:

With the USBASPI.SYS driver, if you specify /E as a parameter,
the driver will NOT find UHCI devices... only EHCI devices! (As
well, if you specify /U, the driver will NOT find EHCI devices...
only UHCI devices, but that's more understandable.) If you
include neither of those switches, it finds all UHCI and EHCI
devices. (The Panasonic drivers behave the same way.)

As i understand the USB specification (but i'm no expert), an
EHCI system can "read" UHCI devices (albeit at UHCI speed). So i
guess the switches /U, /O, and /E mean *exclusively* UHCI,
*exclusively* OHCI, and *exclusively* EHCI.

But since the USBASPI.SYS 2.27x revision loads so fast anyway,
those switches don't offer much loading-speed advantage. Here're
my measurements (flashdisc connected to root hub):

EHCI device:

DEVLOAD USBASPI.SYS /V Elapsed: 1.06 sec
DEVLOAD USBASPI.SYS /V /E Elapsed: 0.94 sec

UHCI device:

DEVLOAD USBASPI.SYS /V Elapsed: 1.10 sec
DEVLOAD USBASPI.SYS /V /U Elapsed: 0.50 sec

Perhaps on a slower system there might be some advantage
nonetheless. (Mine is 2.4 GHz.)

And just as an aside, in my system, the revised USBASPI 2.27x
driver takes 14,864 bytes of RAM when loaded. The Panasonic 2.27
driver takes 15,120 bytes (256 bytes difference).

- Doug B.

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