i want to put a 20MB file in dosubcd.img so that I can run it when freedos boots. However, dosubcd.img has a size limit of 2.88MB. How can I expand the limit? I tried UltraISO and WinImage, neither works for me.

What is kind of file is it? The programs that are booted via the freedos image are files that are not in the freedos image itself (/dosapps/ folder). so if you need this file after the whole freedos image is booted up, you can access the file from the cd.

You can also make a hard disk image of the freedos image (needs and mbr).
See http://syslinux.zytor.com/wiki/index.php/Hard_disk_images.
Or you can try to make a large floppy with a script, but I think that it is limited to 10 MB.
See http://syslinux.zytor.com/wiki/index.php/Large_floppy_images.

I would suggest to try to add the file only on the cd and not in the freedos image. Can you explain what kind of file(s) it is?

Thank you very much for your reply.

It's a PDK folder containing all the utilities to change BIOS info, serial number, run disk test, etc....I need to boot from dosubcd.img, which is on a PXE Server. It's not booting from the CD. Therefore, I need to expand dosubcd.img so that I can put the PDK folder in. BTW, is dosubcd.img bootable by itself(if it is actually a 2.88M floppy disk)?

Now I have learned how to expand the .img file using WIN IMAGE. Howver, after I put the PDK folder in and save the .ima file, gzip it to dosubcd.ima.gz, rename it to dosubcd.igz, and then put it back to ./images/. After reboot, when I select to boot from freedos, it runs until "Loading boot sector...booting....(next line) FreeDos" Then it stops running. Do you know why? Thanks again.

What is a PDK folder?
What does each of those tools need. Need they special drivers or so or do you just need a dos bootdisk? If not, it will be probably easier to start from an installation of freedos installed on the harddisk of a virtual machine.
http://www.freedos.org/

The freedos image of ubcd is bootable of course. If you have a 2.88M floppy disk laying around, you could boot from it.


I don't know, but there must be something wrong. Have you tried to boot the image directly in a virtual machine? See if that works.

Simply put, the PDK folder has syscfg.exe, which can change the BIOS configuration; and edidos.exe, which alters the OEM serial number. I don't think this info is very important though, since what I want is just to expand the size limit of the dosubcd.img AND have it working as usual, i.e. bootable and can run applications as usual. Thank you for your time!