Thanks for the response. I think my issue has something to do with making the ISO image. I used 'dd if=/dev/cdrom of=cd.iso' which made a 676Mb file. But using this file gives me the error. I then tried attaching directly to the cdrom drive in vax.ini using 'attach -r rq3 /dev/cdrom' and it worked! I was able to do a full installation from the actual physical media. Does anyone have any pointers for making an ISO image of the CD? Am I doing it wrong? I would like to make a backup of the disk because I'm already on my second physical copy and would like to back it up before I lose it again :) Ian On 2011-09-05, at 10:20 PM, hvlems at zonnet.nl wrote: While in simh commandmode, show the devices that are seen in simh. Do the same in srm mode: sho dev The boot device type may be DK, RQ or DQ, I forgot You must have typed it in: to assign the hosts cd drive to a iunit name. Verzonden vanaf mijn draadloze BlackBerry -toestel From: Ian McLaughlin <ian at platinum.net> Sender: owner-hecnet at Update.UU.SE Date: Mon, 5 Sep 2011 15:57:38 -0700 To: <hecnet at Update.UU.SE> ReplyTo: hecnet at Update.UU.SE Subject: [HECnet] SIMH on CentOS 5.6 Hello All, I'm trying to compile and run SIMH on CentOS 5.6. I've followed the instructions at http://www.wherry.com/gadgets/retrocomputing/vax-simh.html but when I try to boot from the CD image, I get: [root at zork data]# /usr/local/vax/bin/vax VAX simulator V3.8-1 NVR: buffering file in memory RQ: unit is read only Eth: opened eth0 KA655-B V5.3, VMB 2.7 Performing normal system tests. 40..39..38..37..36..35..34..33..32..31..30..29..28..27..26..25.. 24..23..22..21..20..19..18..17..16..15..14..13..12..11..10..09.. 08..07..06..05..04..03.. Tests completed. (BOOT/R5:0 DUA3 2.. -DUA3 ?42 NOSUCHFILE, DUA HALT instruction, PC: 00000C1A (MOVL (R11),SP) sim> Any ideas about what I might be doing wrong? The CD image file I made directly from the Montagar 7.3 CD. The vax.ini file is exactly as shown on the instructions page. Thanks in advance for any suggestions! Ian --- Filter service subscribers can train this email as spam or not-spam here