View Full Version : help getting from image to boot disk - 11/73

January 7th, 2011, 05:50 PM
I recently "upgraded" a MicroVAX to a MicroPDP-73 and I'm struggling to get it to boot. System has an RQDX3 controller in it, presently hooked up to an RX50 disk drive. I've created a bootable disk image in PUTR and verified that it actually works in E11. I've tried to move it from image to 5 1/4 floppy using PUTR and I can create a disk that I can read back. I've also run PUTR's BOOT command to make it bootable but so far no luck when I try to boot my real system.

Questions -

1) Can I mount my PC floppy drive under E11 as a bootable RX50 drive so that I can verify that my new boot disk truly works before moving from emulator to real hardware?

2) is there a way to do a true "image copy" of my RX50 disk image to RX50 formatted floppy? In PUTR, I've used copy/dev/file/binary boot53.dsk b: and then made the disk bootable but I wonder if there is a way to do a bit copy or dd from image to floppy? Or a way, as in (1) above, to try to boot from my floppy under emulation?

I've tried to do my homework on this but I seem to missing something obvious. I'd really like to make this work with the RX50 (or prove the RX50 bad) but next step is to move on to TEAC "RX33s" and/or messing around with several MFM drives of unknown history. Of course, I'll need to format the hard drives but I _think_ that I can reinsert the MicroVAX CPU and format from the boot rom rather than trying to come up with a bootable XXDP floppy.



January 7th, 2011, 06:54 PM
I gave away the only RX50 drive I had several months ago so I can't help you with anything specific to the RX50. I know I have booted RT-11 and XXDP on my 11/73 from an RX33 floppy but it has been a while now and I can't remember whether I created the floppy from an image created running SIMH on a PC, or whether I booted the 11/73 from a different drive and then created the bootable RX33 from the 11/73.

If I am reconfiguring a system now I typically boot XXDP from a SCSI CD-ROM attached to a CMD SCSI controller.

If you get completely stuck and you have an RX33 or equivalent TEAC floppy drive I could create bootable XXDP and RT-11 RX33 floppies and physically mail them to you.

I could probably also figure out how to create a bootable RX33 floppy from a PC and write up notes on how I did that if you don't have any luck doing that yourself. There must be notes from others on how to do that somewhere out on the net.


Lou - N2MIY
January 8th, 2011, 04:41 AM
Hello Jack,

There was an RX50 in the decmate II I gave you, so don't forget you have that one to try.

When I was in your position, I made bootable RT-11 or XXDP TU58 images, and booted the machine with Will's TU58.exe emulator. Then you can run the XXDP routines on the floppy drives, or zero disks under RT-11 etc... In the worst case scenario, I can mail you bootable media, but the emulated TU58 path is really the way to go.

I just had another thought, which is that when you wrote the files to the disk image under PUTR, are you sure that the boot block got written? (basically like copy /boot under RT-11?)


January 8th, 2011, 06:39 AM
Hi Lou - yes, in fact I'm using that RX50 in these trials. I get a read light on the drive but then a "disk not found" error on the console. I've used both the PUTR boot command nad copy /boot under E11 to create bootable images. It's just the verification step of being able to read the new physical floppy in the emulator that's missing. It might be available in SIMH - I need to look more closely there. Emulated TU58 is another "next step". Just thought I'd try a boot floppy first. It _will_ work eventually!


Lou - N2MIY
January 8th, 2011, 09:29 AM

For peace of mind anyway, that RX50 did work fine in that decmate II. I suspect something is getting fouled up with the boot block on the physical floppies.

Since you have an RQDX3, then you shouldn't feel too bad about using RX33 drives instead. Ok, they weren't made by dec, but they are super robust and have much more capacity.


January 13th, 2011, 06:37 AM
Last night, I was able to semi-boot XXDP from an RX50 disk created in SIMH and loaded to disk with PUTR. The "semi" part means that I got as far as seeing an XXDP header prompt on the 11/73 console and then the system puked out into ODT. At least I now know most of my tools mostly work. At this point, I expect either a media or drive issue, but at least I know I've got the basic steps right.


February 20th, 2011, 07:57 PM
Sorry I haven't been following this. You say the disk you're trying to boot is XXDP?

What vintage of XXDP are we talking about?

A simulated environment is more likely to be forgiving about revision levels of the hardware than a real environment. You say it's going to micro-ODT?

Try hitting "P" [Proceed] (http://en.wikipedia.org/wiki/On-line_Debugging_Tool) a few times and see if it makes it through booting to the prompt. The Dual wide 11/73 cards had bus timeout issues with older software / hardware combinations. I was able to seed my first RQDXn based 73's with old DSD RL drive emulators by using this technique.

If this doesn't work for you, please post a snapshot of how the cards are installed in your backplane.

Only other thing I can think of is to make sure your cards are at standard addresses, particularly the DLV. Is the LTC enabled?

March 2nd, 2011, 07:27 PM
Looks like a good week for getting systems to boot. Tonight, I was able to boot into XXDP on this system. With a new CMD SCSI card (thanks to NeXT) and lots of good info from Glenn Slick, I was able to create an RD54 image in E11, burn it to CD as an .iso image and then boot from CDROM on the real hardware. As usual, several days of fiddling and waiting for ebay booty intervened but it all came together tonight. I went through a small stack of internal and external SCSI CDROM drives, cables and media before achieving success with a Toshiba XM4101B / RRD43-AA drive from WeirdStuff. For the record, several NEC 3x and 6x drives that are reported to work with various Sun and VAX systems did NOT work for me.

The working drives look like DEC pulls and are actually dual labeled with TEAC and DEC numbers. If anyone is interested, WeirdStuff still has 11 more drives in stock as I write this (@ $14.95). Next steps - copy XXDP to RL cartridge to use on UNIBUS systems and then repeat the process with RT-11. At least now I have a known working system to build off of as I start digging into some of the accumulated backlog in my basement.

Thanks to all for your help and support!


March 2nd, 2011, 08:22 PM
You know, when I saw these cards I wondered if anyone was ever going to be crazy enough to try and boot a PDP from a CD.
Thank you for proving it's more than possible. :D

I wonder how old of a system we could manage to boot off a CD using these cards.

March 2nd, 2011, 09:06 PM
Thanks for the tip... there are 9 now...:cool:

Where can I find one of those CMD controllers?

March 3rd, 2011, 06:44 AM
Even though the CDROM drive I used probably came from a VAX, it (the drive) was manufactured in 1994, when you could still buy a new PDP-11. There are several favorable things in play here - a CPU line that stretches back to 1970, open hardware specs (qbus and unibus), well defined software protocols (especially MSCP) and a large user community willing to embrace third-party alternatives. All these combined to make a rich mix-and-match environment that rewarded experimentation and tinkering. If you're willing to play a bit of hopscotch with drives and buses - and I intend to do just that - it isn't too big a step to jump from qbus to unibus and work all the way back to the beginning of the line.

My question at this point is if there are any compatible CD _burners_ that will let me extract images from my system? It may be that running a Unix variant and using dd is the best answer but this is all new territory to me.


March 12th, 2011, 10:04 PM
... With a new CMD SCSI card (thanks to NeXT) and lots of good info from Glenn Slick, I was able to create an RD54 image in E11, burn it to CD as an .iso image and then boot from CDROM on the real hardware...

Is there any way I could get a copy of that ISO file, and the procedure you refer to - that created it?

I now have two of the SCSI CD drives you mentioned. Still looking for a controller card. Jack, did you get my PM?

March 13th, 2011, 01:41 PM
Glen provided me with the process to do this - hopefully he'll post it on his pdp pages. Basically, you create a bootable MSCP image in SIMH by running XXDP from an RL drive, use that software to initalize an RD drive, copy the files to it and then transfer the RD image to CD as a raw image by using the ISO function of your PC CD burning software. At that point, it's just a matter of booting from the CD on the real hardware. Of course, the "just" part assumes a scsi controller on your DEC hardware and an MSCP-aware OS.