mkisofs -b dos_boot.img -no-emul-boot -boot-load-seg 0x07C0 \ -o win31_bootable.iso ./win31_dos_files/
If you cannot find a pre-made ISO that you trust, build your own. This is safer and educational. windows 3.1 bootable iso download
In 1992, Windows didn't come on an ISO; it came on a stack of roughly seven 3.5-inch floppy disks mkisofs -b dos_boot
It’s Windows 3.1—the General Protection Fault (GPF) is part of the charm. However, using a bootable ISO avoids the "Disk 4 is corrupt" nightmare that plagued original physical media. Windows didn't come on an ISO
If you insist on finding an ISO, here is how to spot a good one vs. a virus: