I finally got around to looking at an old Western Digital Passport terabyte USB drive that I was given.
WD 10EACS (MyBook)
Inside there is a WD Green Label terabyte SATA drive.
I first reformatted the drive into a bootable MS-DOS 7.1 USB drive.
Then I copied about 10gb of data to the drive.
After testing the disk with various operating systems I was confident that it was working properly.
From a modern point of view this drive may appear an Otiose Galápagos Tortoise.
Or perhaps, a WDC(Western Digital Caterpillar?)
However, I thought it quite appropriate for older DOS machines.
Since it is a USB 2.0 drive, it should be able to saturate UHCI controller speeds.
I first connected it to and old HP Pentium 945 machine and tested the default Legacy BIOS support with DOS.
Although the drive worked for the better part, there were several files and folders that simply did not appear.
So next, I thought I would give your TSR drivers a try.
I found that at first usbuhci and usbdevic did not appear to notice the drive at all.
However, if another program or driver such as the board's Legacy support enabled the disk first,
usbuhci/usbdevic were able to detect the drive.
$1058 $1100
After that, it looked as though usbdrive was able to view all of the folders on the disk.
Some files copied off the disk just fine.
However, other files data became scrambled when copying them.
For example, some mp3 files that I copied did not play properly.
Still, I think that even partial file read access is rather nice.
However, after a while of testing, I noticed that copying was causing the video page to jump around.
This problem was causing images to be drawn in the wrong places on the screen.
Did you intend to change the Video banks/pages during USB disk access