VAX4000/300 MNS7.3 isntallation from CDROM

Hi, I've got an VAX4000/300 eqipped with an TK70, 2x RF31, 1xRF71 disks, and an CQD-200/TM. I've connected an toshiba Xm5701 drive to the SCSI Bus and the machine sses it as DUA3. I have a VMS7.3 CDROM and want to install it on one of the disks. I've read some documents on HPs website but it isn't clear to me how to boot the cdrom correctly, there is root 1 mentioned. What bootflag must entered, B/R5:10000000? ..in the case w/o the R5:10000000 I get a $ Promt finally (here I habe to read further). With the bootflag the System is complaining that dua3 is write protected (it is the cdrom)... What's the correct way to install VMS on that machine? Regards, Holm -- Technik Service u. Handel Tiffe, www.tsht.de, Holm Tiffe, Freiberger Stra?e 42, 09600 Obersch?na, USt-Id: DE253710583 www.tsht.de, info at tsht.de, Fax +49 3731 74200, Mobil: 0172 8790 741