Hi John, thank you for the idea. I finally managed to boot and install Ultrix 3.0. I prepared a new harddisk image under Ultrix 4.0. I could find /usr/sys/SAS.net/vmunix in the Ultrix 3.0 distribution tapes. This is a standalone kernel that will start the installation process. It can be booted like a normal kernel and can use the 3.0 tape images available from bitsavers. Dennis