Last Updated on April 19, 2023 by Dave Farquhar
You can use FreeDOS to make higher-than-usual capacity floppy disks, including boot floppies. The FreeDOS system files take up half the space of Win9x’s DOS. That extra 100K on the disk can make the difference between your tools fitting on a floppy or not. But it has a few more tricks available as well.
Formatting high capacity floppies in FreeDOS
The FreeDOS FORMAT.EXE can overformat disks. If you use more than 80 tracks, the disks have problems in some machines, but a 1.68 megabyte disk using extra sectors per track should be OK. Concerned about overformatting disks? The Amiga’s default high-density disk format was 1.76 megabytes. That extra 240K can make a big difference, especially when coupled with that 100K you’ve already saved. The syntax to make a bootable 1.68 meg disk: FORMAT A: /F:1680 /S
The syntax for a 1.74 meg disk: FORMAT A: /F:1743 /S
Using FreeDOS and its 1.68 meg floppy, I was able to squeeze Ghost 8.1 (a 1.3 meg monster) onto a boot floppy and still have 197,632 bytes free to play with. With that kind of space left, if need be, one could format the disk with FreeDOS, then SYS it under Win9x and run MS-DOS 7 on it.
Taking high capacity floppies a step further with FDFormat
If you still need to squeeze a little more space, get the freeware FDFormat, which can also format oversized floppies and lets you reduce the root directory down to 16 entries from the default 224, which gives you a few more kilobytes of usable space. If you need to put more than 16 files on the disk, create a subdirectory and put your files in the subdirectory. The syntax would be FDFORMAT /D16 /F168 /S. Substitute /F172 for a bigger disk. To increase the performance of the floppy (who doesn’t want the slowpoke floppy to be a bit faster?) add the /X:2 /Y:3 options. A boot disk formatted this way yields 1,595,904 free bytes with the FreeDOS boot files installed.
David Farquhar is a computer security professional, entrepreneur, and author. He started his career as a part-time computer technician in 1994, worked his way up to system administrator by 1997, and has specialized in vulnerability management since 2013. He invests in real estate on the side and his hobbies include O gauge trains, baseball cards, and retro computers and video games. A University of Missouri graduate, he holds CISSP and Security+ certifications. He lives in St. Louis with his family.
I’ve used tomsrtbt, “The most GNU/Linux on one floppy disk”, and noticed that it formats a 1.44 diskette to 1.722. Quite handy for a minimal bootable Linux.
I haven’t booted to a non-Linux boot disk very often since I last used Ghost. Mostly I boot to a Knoppix CD (a version of Debian Linux) when I want to boot to a non-installed o/s. It can read ntfs, though I’m not sure about write support.
I did find FreeDOS on a bootable CD to be very handy once. I had tried experimenting with dual booting my laptop from work to several Linuxes and one managed to hose the mbr, rendering the Windows install unbootable. No floppy, only a bootable CD. Booted to FreeDOS, did “fdisk /mbr”, problem fixed.
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-Steve
Steve, I don’t know where I got the idea that 1.72 meg disks aren’t bootable because I just formatted one with FreeDOS and it boots just fine. Maybe other versions of DOS don’t like them. Or maybe I had a bad disk the last time I tried it. Anyway, it worked for me, so I’m going to change this entry to reflect that.
Thanks!