VAX-11/730 %BOOT-F-Unexpected Machine Check

Mark J. Blair nf6x at
Mon Jun 8 09:35:45 CDT 2015

> On Jun 8, 2015, at 07:05, Mike Ross <tmfdmike at> wrote:
> On Mon, Jun 8, 2015 at 7:05 AM, Mark J. Blair <nf6x at> wrote:
>> I finally got the excellent AK6DN tu58em emulator working as my VAX-11/730's console drive, as discussed on VCF.
> Could you throw me a link to that please? I have a 730 I'm going to
> have to have a hack at at some point...

Sure! I'll take this opportunity to document a lot of the different pieces that I had to dig up to get this all working.

First, here is Don AK6DN's TU58 emulator:

It's a DEC computer life-saver! I started with v1.4j, and modified it to 1) build on my Mac and 2) remove some delays that caused trouble with the console firmware's very aggressive 20ms IDLE-IDLE to CONTINUE turnaround timeout. Don hasn't had a VAX 725/730/750 to test it against, and it turns out that the 730 didn't like it at first. I've shared my fork here:

Note that the master branch, which comes up by default, is Don's original tu58em code. My changes are on the nf6x branch. I believe that Don plans to update his original code based on this experience, but I don't know yet whether he will do it the same way that I did or take a different approach. Both his original code and my fork are likely to change by the time you get back to your 730. :)

I got my console tape images here:

I also put a copy of those images on my GitHub account, along with some other bits such as the extracted files from them:

I have an RL02 pack of the Customer-Runnable Diagnostics that came with my system, and appears to be compatible with the CRD tape in that set of console tape images. I don't have a way to image it yet, but when I do I will add the image to that repository along with the console tape images.

In working with the images, I learned that the console boot tapes are in RT11 format, but they don't strictly adhere to the RT11 filesystem documentation. They have, variously, spaces or NULs in place of some key fields such as the first directory segment entry of the header block. That was causing my RT11 filesystem utility to blow chunks on them, so I added a hack to it so it can read them now:

I have not yet tried to boot my VAX with a console tape image that has been generated with my pyRT11 code, so I don't know yet whether they will like each other. I figure I may need to experiment with that at some point, for example to change the DEFBOO.CMD as appropriate for my system.

I found some VAX-11/750 console tape images plus a bunch of other TU58 images here:

Since I can't seem to boot up my R80 or my other RL02 pack (labeled "VMS53RL02SYS" on top) yet, I've been trying to bring up the VMS 5.3 Standalone Backup tape images I found there. No luck so far. I have never run a VMS Standalone Backup environment before, but I am blindly hoping that it will be a small VMS environment that will let me try to mount filesystems from my hard drives and see what, if anything, is on them. I would greatly appreciate any clues here, because I'm in unknown waters.

If anybody has relevant TU58 images that aren't already archived at one of the sites above, PLEASE share them and/or point me to where they are! And please make sure they get archived!

Mark J. Blair, NF6X <nf6x at>

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