Due to different versions of Windows 98, USB optical drives, and motherboard hardware, there is no universal solution to have all USB devices supported under DOS. If the Cypress DUSE 4.9 USB drivers are not working for you, you may wish to try the following procedure.
1. Load Windows 98 bootdisk (I recommend the Windows 98 OEM version over the Windows 98SE or DOS 6.22 bootdisk) onto a floppy disk. Verify that the disk is able to boot to A:\ command prompt correctly by inserting it into the floppy drive on the target computer and selecting the floppy drive as the first boot priority.
3. Extract f2h_usb.exe to any directory on your computer. Locate the following files from the root directory, and copy them over to the bootdisk.
USBASPI (v2.15) allows USB connected mass storage devices to be mapped as ASPI devices.
4. Download "Motto Hairu" driver (Assigns drive letter to an ASPI mass storage device) from the following location:
5. Extract the filename below from mhairudos.zip onto the bootdisk. Do not extract the USBASPI.SYS and RAMFD.SYS located in mhairudos.zip onto the floppy.
6. Right click on AUTOEXEC.BAT and select "Edit" to edit the file in Notepad. Remove all the information contained within, and replace with the text below. Save the file with the same extension (.BAT). mscdex.sys can be configured to assign a drive letter starting from a certain letter using /l: as a parameter. In this example "M" is the first drive letter to be assigned.
mscdex.exe /d:mscd001 /d:USBCD001 /l:M /M:16 /v
7. Right click on CONFIG.SYS and select "Edit" to edit the file in Notepad. Remove all the information contained within, and replace with the text below. Save the file with the same extension (.SYS).
device=USBASPI.SYS /v /w
8. Now you are ready to boot from the bootdisk. When the bootdisk loads, it will assign drive letters for each USB mass storage device starting from the drive letter you specified earlier in AUTOEXEC.BAT or CONFIG.SYS.