If you want to transfer files between a Nameless OS virtual machine and a different OS, use the tar command.
Nameless OS tar is simplistic but pretty standard. For example, you can use a tarball as a floppy or a hard disk image. Nameless OS tar operates on /dev/rdsk/fd0,0 (first floppy disk drive) by default.
Tarballs may need to be extended to the correct size before you can use them as disk images.
If you want to add a file to the OS itself, put the file somewhere in the "tree" subdirectory of the source code. If you want the file to be installed as a part of the OS, add an entry in "tree/etc/sysinstall.copy". If the file is a program, you may want to put the source code in "cmd/bin" or "cmd/sbin" and modify a makefile so that the program is compiled when the OS is built.
Finally, if you happen to want to transfer files between Nameless OS virtual or physical machines, you can use floppies and the file manager GUI. To create a Nameless OS file system on a floppy use the following command:
mkfs /dev/fd0,0 2880