I see that you would like to use HP CD-Writer Plus External 7200e Drive for installing Windows 98 in the system and need assistance regarding the drivers compatible with DOS to function External USB drive.
Let me assist you in this regard.
At this time, please refer the URL below for making USB boot floppy disk and boot into DOS.
NOTE: The URL(s) above will take you to a non HP Web site. HP does not control and is not responsible for information outside of the HP Web site.
After performing the above options, please follow the steps below to install Windows 98 in the system.
== USB cdrw Recognition in DOS :
1. Use the Windows 98 boot disk and boot to command prompt
2. fdisk the hard drive and create a primary partition, reboot
3. Boot up with the same Windows 98 floppy and go to command prompt
4. format c:
5. Insert your Windows 98 cd in the cdrom drive, reboot with your "USB DOS CD-ROM BOOT DISK"
6. C: is your hard drive, and your CDROM drive most likely will be mapped as D:
8. D:\setup.exe for 98.
If you don't want to see the "Insert diskette for drive..." message, then go edit autoexec.bat on your USB DOS CD-ROM BOOT DISK
Between the lines
duseldr a:\duse.exe and MSCDEX /D:USBCDROM /S /M:15 /V
there is a B: line to change drive, Remove it out.
This may resolve the issue.
I hope this information helps you. Please reply if I can help you further. I would like to add that we value your precious time and would be here round the clock to serve you.