Resurrecting an ST-225 from a DEC Pro

[Andrew Hudson]

First let me say that the MFM emulator is pretty darn slick. I was awestruck when I found out about it. I have 3 disks with errors I am working on, different disks. Disk 1 is an ST-225 from a DEC Pro that was recognized and partially imaged. It looks like it errored out before completing. I'm looking for suggestions to correct for the errors. Two screen shots of the output are attached. 

[Tim Radde]

I have a DEC Pro-350.  I will do what I can to assist.  But I am not an expert on how to repair partial reads.  It may be those sectors are not in use?  And maybe

it will still work?  Did it create the file?

[d...@pdp8online.com]

The messages  show that on the last cylinder the sector header has a sector number higher than expected. It also wasn't able to decode properly any of the sectors on the track. This may be the pro only formatted 614 cylinders so the last cylinder is some old data in another format. The other pro images I have don't have this funny cylinder.

Not shown you likely have a few more sectors with errors since says 66 sectors with errors and last cylinder would only be 64.

You can attempt to decode the last cylinder mfm_util --analyze --emulation_file PO53_a --ext lastcyl

If it find the format for the last cylinder it won't match the rest so all except the last cylinder will give errors.

The emulator data file will have the last cylinder. You can't tell if it had read errors but if needed by the Pro it will be there.

[Andrew Hudson]

The first image resulted in a segmentation fault when I tried to emulate it to the Pro. So I did another read, which resulted in this endless loop of errors: 

Ran out of data on sector index 16, try adding --begin-time 426000 to mfm_read command line. 

[David Gesswein]

Attaching a file with the full set of messages will make interpreting them
easier.

Was it really a segmentation fault or was it the dump of hex data where
the software aborts when internal consistency checks fail? Either should
be investigated.

Not sure why it would be complaing about --begin_time if your reading
the same drive as last time. That message indicates that the index pulse
occured in the middle of a sector. --begin_time shifts the read timing to
prevent that. Was it only on the last cylinder or earlier? If earlier did
you try adding --begin_time?

On Wed, Oct 30, 2024 at 07:47:59AM -0700, Andrew Hudson wrote:
> The first image resulted in a segmentation fault when I tried to emulate it
> to the Pro. So I did another read, which resulted in this endless loop of
> errors:

> *Ran out of data on sector index 16, try adding --begin-time 426000 to
> mfm_read command line. [image: MFM_POS3.jpg]*

>
> On Tuesday, October 29, 2024 at 11:01:01 PM UTC-4 timr...@gmail.com wrote:
>
> > I have a DEC Pro-350. I will do what I can to assist. But I am not an
> > expert on how to repair partial reads. It may be those sectors are not in
> > use? And maybe
> > it will still work? Did it create the file?
> >
> > On Tuesday, October 29, 2024 at 8:56:18 PM UTC-5 ahuds...@gmail.com wrote:
> >
> >> First let me say that the MFM emulator is pretty darn slick. I was
> >> awestruck when I found out about it. I have 3 disks with errors I am
> >> working on, different disks. Disk 1 is an ST-225 from a DEC Pro that was
> >> recognized and partially imaged. It looks like it errored out before
> >> completing. I'm looking for suggestions to correct for the errors. Two
> >> screen shots of the output are attached. [image: MFM_POS1.jpg][image:
> >> MFM_POS2.jpg]
> >
> >
>

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[Tim Radde]

What OS is installed on your Pro?  POS or something else?  Mine has RSX-11 on one disk and I was told POS is on the other.  Never used POS and from what I read

I would not want to so this is a spare for now.  

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[Andrew Hudson]

This disk was reformatted and P/OS was installed over the previous contents. The data on the last cylinder may not be important. 

However the first image caused a segmentation fault and the second attempt to image goes into a loop and does not complete. 

Thanks for any advice on how to proceed or quit. 

[Andrew Hudson]

P/OS 3.2 is installed, which is a version of RSX-11M. I'd like to start archiving OS images for the DEC Pro. There are at least the following that were ported at one time: P/OS, RT11, Xenix, BSD, Ultrix-11, even RSTS/E. 

[Andrew Hudson]

I run P/OS using the command line to do programming. I don't use the graphical interface but do want to do graphics programming. 

The video system on the Pro was pretty advanced for its time.

[Tim Radde]

I have lots of floppies with Pro stuff on them.  No idea how to archive them yet.  POS may be fine but I don't care for menu driven systems.  RSTS can run on a 

Pro?  I would think that would require a Pro-380?  I would enjoy putting RSTS on my Pro if it would run.

[d...@pdp8online.com]

Did you see my reply?

[Andrew Hudson]

Hi Dave,

I was able to image the ST-225 with the P/OS image by providing override values:

I used: 

mfm_read --sectors 16,0 --heads 4 --cylinders 615 --header_crc 0xffff,0x1021,16,0 -data_crc 0xffff,0x1021,16,0 -sector_length 256 --retries 60,4 --drive 1

I confirmed it by booting from the emulator. It worked great and was so much quieter than the  MFM disk! 

I am still working on imaging a rare Ultrix-11 image from a ST-412 RD51-A. 

[Tim Radde]

My Pro-350 run RS-11XM and I have imaged that drive and it runs just fine.

[Andrew Hudson]

Hi Tim, 

Just to be clear, you have an install for RSX-11M, not P/OS? Do you have any documentation on it? I'm guessing it is command line and similar

to command line in P/OS? Is there any chance you can post a link to it on OneDrive or GoogleDrive?  Thanks!

[Tim Radde]

I am not the person that set up my Pro-350.  It was given to me by a friend before he moved and he wanted some of his stuff to go to a good home.

There were 2 disks in the Pro.  One has RT-11XM and the other I was told has POS.  He had added a power switch to switch between using either

drives.  I never tried to boot POS as it just doesn't suit me.  It is command line.  I guess it's like a single user RT-11.  I do not have to log in.  Once booted

I am in RT-11 and can run commands.  I am no expert with RT-11 so have not done much there yet.  I would have to guess that somewhere in my 

stack of floppies he gave me is the actual install disk for this OS.  That's another reason I wanted to dump to the MFM emulator.  In case it crashed

and I did not have the install media. I got docs for the Decmate and the Rainbow but nothing for the Pro.

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[Andrew Hudson]

Ah, OK, you have RT-11. There are some guys on VCFED who have written some basic graphics programs for RT-11. You can find their 

thread on VCFED.org. There is a mandelbrot program, a Pi calculator, and even a picture display program. 

[hupfadekroua]

@Andrew, I‘d very interested in an Ultrix-11 Image.

Best

Andreas

Am 04.11.2024 um 15:59 schrieb Andrew Hudson <ahuds...@gmail.com>:



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[cub...@gmail.com]

I would be interested in an Ultrix image as well.  I have v7m 1.0 floppies (which I also contributed to Bitsavers - one can download it from there) and loaded up an RD51 (actually an IBM XT drive), and it boots, but hangs or panics on my 128Kw Micro PDP-11/23.  I have transferred it to my PC to play with it under SimH, wondering if maybe it is tripping over something in the hardware.

The floppy images are at https://bitsavers.org/bits/DEC/pdp11/floppyimages/rx50/

JRJ