Installing ULTRIX/VAX V4.5 on SIMH/VAX V3.0-2

Read this page if you want to:

  There is an alternative way to install ULTRIX/VAX on SIMH. Please check out this first, before trying my more complex method described below! I've made a local copy of the original message that was posted on TUHS' mailing list.

Then you need the following:


One would think it's pretty straight forward to install ULTRIX V4.5 on top of the very impressive hardware emulator SIMH. But when I tried to do a plain CD-ROM installation I discovered that the ULTRIX SAS kernel didn't recognize any installable disks, i.e. the installation program could not continue.

With a little tweaking it's possible to get around this obstacle, you need to do a manual installation. Follow the steps below to get ULTRIX 4.5 up & running on your peecee running Window$. If you make appropriate alterations to the procedure you should be able to use any *NIX platform as host operating system (but of course limited to the platforms that SIMH can be built for). These instructions may apply to other-than-4.5 versions of ULTRIX, but this has not been tested.

Steps to be followed on your real VAX

  1. To get the biggest supported VAX system disk for your emulator, begin with formatting one of your disks in your VAX as a DEC RA92 which is about 1.5 GB. The geometry is found in /etc/disktab in ULTRIX. It's enough if the 'c' partition has the same size as on RA92, and there are no partitions beyond the end of 'c'.

  2. Install ULTRIX V4.5 on that 1.5 GB disk and keep the existing disklabel. This can be done through ULTRIX installation program or through a manual installation (by copying your existing ULTRIX system disk, using 'dd' at least for the root partition).

  3. Create a new fstab with 'ra0' devices, for example as /etc/fstab.emu on your new disk. This will make it a bit easier, later.

  4. Go to /dev and ./MAKEDEV ra0 on your 1.5 GB disk.

  5. Now reboot your VAX, and start from your old system disk and 'dd' the unmounted 1.5 GB disk to a file. Use bs=512. In ULTRIX this takes a very long time (over an hour, IIRC). If you are copying your one and only VAX disk you probably need another computer with SCSI to do this (It may work to do this in Single User Mode from the same disk you are dd:ing from, but then you need to 'dd' to some NFS filesystem somwhere on another computer)

  6. Tranfer your disk image file to your Window$ box.

Steps to be followed on your peecee

  1. Download and install WinPcap_3_0.exe from to get ethernet support.

  2. Download and install SIMH 3.0-2 from You need the files and

  3. Start SIMH/VAX using this script start_vax, emulating a MicroVAX 3900 with 64MB RAM, 2 x RA92's, RRD40, RX50 and a DELQA ethernet interface. Place the script in the SIMH directory on your peecee, and execute with 'vax start_vax'.

  4. At the VMB prompt, boot the 'genvmunix' kernel:  You will get some error messages during boot but you'll get to the Single User prompt.

    VAX simulator V3.0-2
    RQ: unit is read only

    KA655-B V5.3, VMB 2.7
    Performing normal system tests.
    Tests completed.
    >>>boot /r5:00001 dua0
    (BOOT/R5:1 DUA0


    Ultrixboot - V4.5  Sun Sep 17 13:03:13 EDT 1995

    Enter image name: genvmunix
    Loading genvmunix ...

  5. Go to /etcand rm fstab; mv fstab.emu fstab

  6. Do mount /usr; vi rc.local and vi hosts to set a new hostname for your system. You may need to use the 'h', 'j', 'k' and 'l' keys to move the cursor in vi, since you are using a dumb console. If you are not familiar with vi, then RTFM ;-).

  7. IMPORTANT! Do a netsetup install and set your ethernet interface to qe0. If you are running SIMH without ethernet support you will need to add a console by adding a line  in /etc/ttys (otherwise you can't login in Multiuser Mode).
  8. Now halt and reboot your emulated system. At this point your emulated VAX should boot up to Multiuser Mode.

  9. telnet to your emulated MicroVAX and configure a new kernel. 'doconfig' doesn't work, so you need to manually edit a suitable config file. You can use mine, EMUVAX. Go to /usr/sys/conf/vax and place your config file there. Then do config <name-of-config-file>. Then go to ../../VAX/<name-of-config-file> and do make depend; make. This will build a new kernel for your emulated MicroVAX, it will take a couple of minutes.

  10. When the build has completed, replace your old kernel by mv vmunix /vmunix.

  11. Reboot your emulated system. Now you should be able to run ULTRIX/VAX as if it would have been installed by the installation program. Congratulations!
Note! It's generally a good idea to keep a working backup of your emulated system's disk image, in case your ULTRIX gets broken. It's an emulated environment so it's not 100% like a real VAX. It's easy to make a backup and pretty much work to make a new 'dd' image ;-)

X-window system

If you want to run X11/DECwindows by connecting to you emulated MicroVAX you need to install an X server for Window$. The SIMH emulator doesn't have any framebuffer.  Here are some links to a few of them: I've also found a set of "patches" that will give you a complete X-server made by DEC; PATHWORKS eXcursion. No license files / serial numbers are required. If you run Alpha NT this is the link for you, there are both alpha-win32 and intel-win32 binaries. 

Feel free to drop me an email if you have found these instructions useful!

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Last updated:  12-9-2006