It seems on systems using the 845G chipset and 82801DB/DBM, the USB2.0 port cannot be mapped by USBASPI.SYS v2.01 from Medialogic (from DAToptic Speedzter DOS USB/Firewire boot disk).
The error obtained is
ERROR : EHCI memory mapped I/O can not assigned.
ERROR : Target USB device not found.
However, when using the USBASPI.SYS v2.06 from Panasonic Japan, it is properly mapped to
MEM=FFA00800h-FFA00BFFh(1024Bytes)
Once the EHCI driver is loaded and the ASPI device subsequently detected, either DI1000DD.SYS or NJ32DISK.SYS will succesfully detect the USB disk drive.
So clearly, there is a difference between Medialogic and Panasonic driver, with the latter having more switch and configuration options.