• Please review our updated Terms and Rules here

Dumping magnetic tapes?

Bitly

Experienced Member
Joined
Sep 1, 2016
Messages
87
Location
Westminster, Colorado
I connected my TZ30 to a linux box and after my rooting around in various boxes to find an appropriate terminator, I bodged together a working setup. The tape is responsive, and I seem to be collecting the right data using 'dd if=/dev/nst0 of=blkxxxx bs=32768 count=1', but I'd like to automate the process without writing a bunch of code (mostly to handle errors). I also have TU58's (easy), and 9-Tracks (hard) to dump as well. The 9-Tracks will require getting an ultrix box running, but that's a winter project (free heating!).

Is there any (linux) software to read a real magnetic tape and write the appropriate .TAP file? I don't see anything in open-simh/simtools.

Any guidance moving forward?

Thanks,
CW
 

Chuck(G)

25k Member
Joined
Jan 11, 2007
Messages
40,275
Location
Pacific Northwest, USA
The practical problem is that dd doesn't preserve block boundaries. If you're using the tape as a .tar source, it may not matter. Also, dd may not be very happy or know what to do with tape label records.
Converting to and from something like SIMH .tap format preserves all that stuff.
 

Al Kossow

Documentation Wizard
Joined
Sep 1, 2006
Messages
2,912
Location
Silicon Valley
Is there any (linux) software to read a real magnetic tape and write the appropriate .TAP file? I don't see anything in open-simh/simtools.


just beware that SCSI tape drives do not recover the data inside of a bad block

use the smallest blocking factor you can to avoid good physical blocks getting lost if one block is bad
 

Bitly

Experienced Member
Joined
Sep 1, 2016
Messages
87
Location
Westminster, Colorado
I'm using a generic SCSI-1 adapter to the TZ30 in my last remaining PCI equipped chassis.

VMS backup tapes are a mix of 80 byte headers and 8K byte data records, but disk save sets are just data (I think). The TAP format should allow me to access the savesets directly in simh, but I'm also working on patches for vmsbackup to work with TAP files also.

When doing research regarding dumping (and writing) 9-track tapes with my SCSI Cipher tape drive, I came across the following post... I wonder if this st.exe utility might work better for you?

This could be a last resort option. I have a DOS capable machine (win98 now) and and ISA SCSI adapter, but it would be difficult to move the data off the machine (no ethernet or USB). I don't think any of my newer machines will run DOS, let alone getting an ASPI driver for them.

Edit: Hmmm, I wonder if either of my Cipher's are SCSI. That would make dumping 9-tracks much easier....

just beware that SCSI tape drives do not recover the data inside of a bad block

use the smallest blocking factor you can to avoid good physical blocks getting lost if one block is bad

I'm hoping to find a utility that will detect and report on bad blocks so I only lose one. I'll root around on Eric's github and see what I can find. Worst case I can write something.

CW
 

Chuck(G)

25k Member
Joined
Jan 11, 2007
Messages
40,275
Location
Pacific Northwest, USA
I can give you a DOS program that uses SCSI (ASPI driver) to create TAP files. I may have a Linux version, but I'm not sure about it. Like Al says, SCSI has its own issues. I prefer Pertec interface drives.
 

thunter0512

Experienced Member
Joined
Sep 27, 2020
Messages
487
Location
Perth in Western Australia
Here is a tiny C program to read a 9-track tape on SCSI tape drives on BSD variants (NetBSD, FreeBSD etc.) and convert it to TAP format.
The assumption is that you are running this on a 32-bit little endian system (i.e. a PC).
No error checking whatsoever is done, but it worked well enough to convert all my CDC CYBER tapes and it took me about 5 minutes to write the program.
If your tape drive or tapes are bad you might want to add some form of error checking/handling.
 

Attachments

  • mag2tap_bsd.zip
    881 bytes · Views: 5

Bitly

Experienced Member
Joined
Sep 1, 2016
Messages
87
Location
Westminster, Colorado
Here is a tiny C program to read a 9-track tape on SCSI tape drives on BSD variants (NetBSD, FreeBSD etc.) and convert it to TAP format.
The assumption is that you are running this on a 32-bit little endian system (i.e. a PC).
No error checking whatsoever is done, but it worked well enough to convert all my CDC CYBER tapes and it took me about 5 minutes to write the program.
If your tape drive or tapes are bad you might want to add some form of error checking/handling.

Thanks. I found a program online (timage.c) that double buffers, and was able to read a couple tapes before everything started going wrong.....

A tape glued itself to the head, got the cartridge out, took the drive apart and cleaned the heads, then the PC wouldn't power on (dead motherboard apparently). Got another system assembled, but still can't read tapes. I need to take the drive apart again and see if I mis-aligned the head connector when I re-installed it. I'm beginning to question my sanity during all this.

I also put a couple tapes in my makeshift easy-bake oven (3D printer with the bed set to 40c) to see if I could de-sticky the media.

CW
 

Al Kossow

Documentation Wizard
Joined
Sep 1, 2006
Messages
2,912
Location
Silicon Valley
> A tape glued itself to the head

I hope there is nothing on the tapes that matters
I've been doing this for decades, and it really annoys me when amateurs make the same mistakes.

Google "cyclomethicone"
 

Al Kossow

Documentation Wizard
Joined
Sep 1, 2006
Messages
2,912
Location
Silicon Valley
> A tape glued itself to the head

I hope there is nothing on the tapes that matters
I've been doing this for decades, and it really annoys me when amateurs make the same mistakes.

Google "cyclomethicone"

"3D printer with the bed set to 40c" will not do a damn bit of good without air circulation other than warping the reel
 

Chuck(G)

25k Member
Joined
Jan 11, 2007
Messages
40,275
Location
Pacific Northwest, USA
I bake tapes at 58C ±0.5C in a purpose-built oven with a fan ensuring air circulation, which seems to be a minimum. But yes, what Al said about Decamethylcyclopentasiloxane.

Let the amateurs make mistakes, so long as the data isn't important and one-of-a-kind, I say... :)
 

Bitly

Experienced Member
Joined
Sep 1, 2016
Messages
87
Location
Westminster, Colorado
I bake tapes at 58C ±0.5C in a purpose-built oven with a fan ensuring air circulation, which seems to be a minimum. But yes, what Al said about Decamethylcyclopentasiloxane.

Let the amateurs make mistakes, so long as the data isn't important and one-of-a-kind, I say... :)

Thanks for the info Al & Chuck!

I do have a fan to circulate the air and an enclosure to keep the heat in. I'll try a higher temperature and see if that improves matters. The 40c was based on the max storage temperature for the tape, and I didn't want to push it on the first attempt.

I'm currently playing with some old backup tapes from a company I worked for ~25 years ago, so no concerns regarding the value of the data. If I can't get a reliable system in place, I'll send tapes that aren't online to someone for recovery.

Clint
 

geerol58

New Member
Joined
Jun 29, 2019
Messages
6
Location
Winssen, NL
I also have TU58's (easy), and 9-Tracks (hard) to dump as well.
In 2022 (and a few years back) your chances on TU58 are quite bad. They moisture even when taking one new out of a box. Reading a TU58 requires going up and down the tape 4 times. You may try dd and the skip option to read these four parts seperately and clean the head in between the parts. (Haven't tried that myself)
9 Track 1600BPI: less than 50% chance depending on the way they have been stored and the quality of the tape (some brands are better). Moisture and sticking to the tape guidance as others decribed.
In all cases: the first attempt to read may (m a y) be the best one: hence convert to .TAP and examine the tape on a SIMH/xxx machine later. If tape tension is the problem, going up and down may help retensioning. In that case the second attempt may be more successfull.

Find attached the progs I made and use for reading tapes. Also find atip and rtip that read and write 9 track tapes or TK50/70 for |d|i|g|i|t|a|l| operating systems RSX, VMS and RT11. These are old programs I made previous century... I use them on virtual tape drives most.

Geert
 

Attachments

  • tapprog.zip
    4.1 KB · Views: 1
  • Atip.zip
    21.6 KB · Views: 2

Chuck(G)

25k Member
Joined
Jan 11, 2007
Messages
40,275
Location
Pacific Northwest, USA
I've routinely done 7 track early 1960s tapes. Prep and treatment is everything--almost.

If you send me a box of Wabash 1/2" tapes, I'll either (a) quote you a very high figure for price or (b) send the box back.

That being said, some of the older tape brands were exceptional. Audio Devices, Graham Magnetics come to mind. IBM-branded tapes were pretty good, particularly the IBM 500 series. 3M/Scotch can sometimes suffer binder bleed, which makes it necessary to lubricate the tape after baking. I generally do this using a thick felt wiper saturated with D5 applied while in the cleaning machine. After reading a tape, the D5 will evaporate slowly, but the drive will need cleaning.
 
Last edited:

cchhrriiss11

Experienced Member
Joined
Oct 19, 2019
Messages
91
Location
Duncan, BC
On the topic of 9-track tapes... are there any particular "new old stock" ones to look for? Any leads?

I've seen a few different listings on eBay for "new" and "sealed" 9-track tapes... I'm just looking to write tape images from Bitsavers, etc for my PDP's.

Obviously, even though they may be NOS/Sealed, I'm assuming they could be suffering all sorts of issues like described in previous posts above.

Thanks -
 

Hugo Holden

Veteran Member
Joined
Dec 23, 2015
Messages
3,049
Location
Australia
I'm beginning to question my sanity during all this.

CW
Welcome to vintage computing and tape data recovery problems.

About 25 years ago I watched as historical analog video tapes from the 1970's and 1980's era had degraded so far that the dipoles had randomized to noise. It is really obvious with analog recordings as the degradation is so visible. Of course aggravated by episodes of tape damage where the tape had stuck to the heads or the tape got creased and later that decreased the head tape contact, causing more signal dropouts.

Only in the last 5 years I have started examining recorded vintage digital computer program tapes. They are a little more immune from age related damage than analog ones. Partly because of the very high record energy levels. But still, as they degrade, whether or not the data can be recovered depends highly on the playback system and the condition of the tape.

If the format of the recording is known, it can be possible to create a custom playback system at the hardware level, which can gate out noise and defects and look for signal transitions where they are "expected to be". Unfortunately any "noise rejection" system still won't work, if there is a vey large section of damaged tape.

My view of this problem currently is that we (as a vintage computer community) need to get as many vintage tape programs recovered ASAP to new media, or the increasing entropy that these old tapes are experiencing, every day, will mean that they will be lost to the sands of time, for good, in the next 10 to 20 years.
 
Last edited:

Chuck(G)

25k Member
Joined
Jan 11, 2007
Messages
40,275
Location
Pacific Northwest, USA
On the topic of 9-track tapes... are there any particular "new old stock" ones to look for? Any leads?

I've seen a few different listings on eBay for "new" and "sealed" 9-track tapes... I'm just looking to write tape images from Bitsavers, etc for my PDP's.

Obviously, even though they may be NOS/Sealed, I'm assuming they could be suffering all sorts of issues like described in previous posts above.

When I need to patch on a new leader, I use NOS 3M "Black Watch" tape. Seems to have survived pretty well.

Hugo, most of everything I worked on in the mainframe world is dust. AFAIK, no copies were ever preserved--and I worked for a mainframe manufacturer. The amount of tape used between 1960 and 1990 must number in the billions of reels. There's probably plenty still out there, although the content is a matter of conjecture.

In particular, I wonder how much of the tape has survived from this period from the national laboratories (e.g. Los Alamos, Argonne, Livermore, Berkeley). Probably all incinerated at one time in the interest of security.
 
Top