From How to make a bootable OpenBSD CD on www.shockley.net
On a Unix machine with the files in /iso/openbsd/3.4

# mkisofs -v -r -l -L -T -J -V "OpenBSD-3.4" -A "OpenBSD v3.4-Release, Custom ISO, 2004-01-15." -b i386/cdrom34.fs -c boot.catalog -o openbsd-i386-3.4.iso -x openbsd-i386-3.4.iso /iso/openbsd/3.4/ On a Windows machine with the files in c:openbsd3.4 c:isotoolsmkisofs -v -r -T -J -V "OpenBSD-2.8" -b c:/openbsd/3.4/i386/cdrom34.fs -c boot.catalog -o c:/openbsd/openbsd-3.4.iso -x c:/openbsd/openbsd-3.4.iso c:/openbsd/.