Re: TU58 yet one more time

[Mark J. Blair]

The Plastibands that I tried were about half the width of the original belt 
once stretched into place, and they would not stay centered on the pulleys or 
tape spools at all. Once they slipped, after just a few turns of the roller, 
they tangled things up badly.
-- 
Mark J. Blair, NF6X 
http://www.nf6x.net/

Re: TU58 yet one more time

[shadoooo]

Hello,
I would need some clarification about the Plastibands, as I will have to find a 
suitable replacement for the belt,
as ALL my cartridges need a replacement, after removing the old one without 
causing the infamous blank-spot.

Al, please could you clarify which size / brand of (Baumgarten) plastibands did 
you use for the TU58 cassette?

Mark, I'm not sure that a wider belt would work better, maybe worse. In fact 
pulley / belt mechanisms usually work with
pulleys that have a bigger diameter near the center than on the sides, 
resulting slightly convex.
Because of physical friction forces, an "unbiased" flat belt will always remain 
exactly in the center of the pulleys.
If a cylindrical pulley will be used, this effect will not be present, so the 
belt will slide off the pulleys.
On TU58 as in DC100 tapes AFAIK the belt is narrow, maybe abound the half the 
width of the pulleys.

Thanks
Andrea


I tried using plastibands in a TU58 cartridge, with zero success. Once stretched, 
the width of the plastiband was too narrow, and > it kept on slipping off the 
edge of the tape spool and jamming things up thoroughly. These are the ones I 
tried using:


> 
http://www.amazon.com/Baumgartens-8-inch-Plastibands-BAUSF5000-Assorted/dp/B0008GIKQW



I think they might have worked if they were at least twice as wide, at around 
the same circumference. Is there a different type
available that might work better?

Re: TU58 yet one more time

[Mark J. Blair]

> On May 31, 2016, at 09:35 , Al Kossow  wrote:
> 
> 
> 
> On 5/31/16 8:38 AM, Mark J. Blair wrote:
>> 
>> If I could find a way to create new tape belts, then it would be nice to be 
>> able to overhaul old cartridges.
>> 
> 
> plastibands work ok for DC-100 carts. the bigger size is a bit too narrow for 
> DC-600 though


I tried using plastibands in a TU58 cartridge, with zero success. Once 
stretched, the width of the plastiband was too narrow, and it kept on slipping 
off the edge of the tape spool and jamming things up thoroughly. These are the 
ones I tried using:

http://www.amazon.com/Baumgartens-8-inch-Plastibands-BAUSF5000-Assorted/dp/B0008GIKQW

I think they might have worked if they were at least twice as wide, at around 
the same circumference. Is there a different type available that might work 
better?


-- 
Mark J. Blair, NF6X 
http://www.nf6x.net/

Re: TU58 yet one more time

[Mattis Lind]

tisdag 31 maj 2016 skrev Al Kossow :

>
>
> On 5/31/16 1:25 PM, Mattis Lind wrote:
> > A simple teqnique that I used sucessfully when reading S8000
> > tapes.
> >
> >
>
> so did you ever get your S8000 running?
>
>
It depend what you mean. It was running fine just 25 years ago. So yes it
was running. But since then I haven't tried. Before I fire it up again I
need to give it a complete overhaul. Check PSUs etc. Just hopefully the old
Finch drive is still doing fine.

The purpose of this tape-reading is to find a method to make a copy of the
tapes without having a running system.

/Mattis

Re: TU58 yet one more time

[Al Kossow]

On 5/31/16 1:25 PM, Mattis Lind wrote:
> A simple teqnique that I used sucessfully when reading S8000
> tapes.
> 
> 

so did you ever get your S8000 running?

Re: TU58 yet one more time

[Mattis Lind]

tisdag 31 maj 2016 skrev Al Kossow :

>
>
> On 5/31/16 9:34 AM, Al Kossow wrote:
> >
> >
> > On 5/31/16 8:38 AM, Mark J. Blair wrote:
> >>
> >> Transferring the tape to be imaged into an audio cassette housing, and
> then imaging it on a hacked up transport
> >
> > You may want to use a data cassette like the MT-2ST
> > http://www.ebay.com/sch/161622290065 has a decent picture. I've got the
> manual on bitsavers
> >
> >
>
> the problem is head width and position. i'd have to check if the DC-100
> carts being talked about (DEC and HP) all
> put the heads in the same place with the same width. the problem with
> using QIC transports is the head width is too
> narrow for the old carts, reducing the contact area and increasing the
> chance of dropouts.
>
>
On the other hand it is possible to shift the position of the head and
thereby circumvent drop-outs by splicing together reads from many different
tracks. A simple teqnique that I used sucessfully when reading S8000
tapes.

/Mattis

Re: TU58 yet one more time

[Mattis Lind]

tisdag 31 maj 2016 skrev Al Kossow :

>
>
> On 5/31/16 12:07 AM, Mattis Lind wrote:
> > tisdag 31 maj 2016 skrev shad >:
> >
> >> However if one
> > sacrifice the entire drive and just use the mechanics it would be really
> > dumb
>
> I don't get it. Why don't you do this with the TU58 mechanism?
>
>
>
Because I want it to be as generic as possible. If it is possible to move
the heads I can read tapes that are written not only by a TU58 but also on
a any DC100 compatible device.  I dont know what sort of head HP made use
of for their HP9825 and HP2645 for example.

I here compare what AJ have done with a Wangtek 5099 drive. Being able to
read a tape written by a completely different drive (DEI) by just
positionig the head correctly. The resulting data I then decoded in
software and the original tar archive was recovered. Now the encoding was
MFM in th S8000 not GCR which was used normally by the QIC-02 and SCSI
drives with nine tracks and DC300.

/Mattis

Re: TU58 yet one more time

[Al Kossow]

On 5/31/16 9:34 AM, Al Kossow wrote:
> 
> 
> On 5/31/16 8:38 AM, Mark J. Blair wrote:
>>
>> Transferring the tape to be imaged into an audio cassette housing, and then 
>> imaging it on a hacked up transport
> 
> You may want to use a data cassette like the MT-2ST
> http://www.ebay.com/sch/161622290065 has a decent picture. I've got the 
> manual on bitsavers
> 
> 

the problem is head width and position. i'd have to check if the DC-100 carts 
being talked about (DEC and HP) all
put the heads in the same place with the same width. the problem with using QIC 
transports is the head width is too
narrow for the old carts, reducing the contact area and increasing the chance 
of dropouts.

Re: TU58 yet one more time

[Al Kossow]

On 5/31/16 8:38 AM, Mark J. Blair wrote:
> 
> If I could find a way to create new tape belts, then it would be nice to be 
> able to overhaul old cartridges.
>

plastibands work ok for DC-100 carts. the bigger size is a bit too narrow for 
DC-600 though

Re: TU58 yet one more time

[Al Kossow]

On 5/31/16 8:38 AM, Mark J. Blair wrote:
> 
> Transferring the tape to be imaged into an audio cassette housing, and then 
> imaging it on a hacked up transport

You may want to use a data cassette like the MT-2ST
http://www.ebay.com/sch/161622290065 has a decent picture. I've got the manual 
on bitsavers

Re: TU58 yet one more time

[Al Kossow]

On 5/31/16 12:07 AM, Mattis Lind wrote:
> tisdag 31 maj 2016 skrev shad :
> 
>> However if one
> sacrifice the entire drive and just use the mechanics it would be really
> dumb

I don't get it. Why don't you do this with the TU58 mechanism?

Fw: TU58 yet one more time

[Tony Duell]

Yes, it's still me. My normal ISP seems to have installed spam
filters (without warning me!) which (a) drop the classiccmp messages
and (b) bounce most outgoing mail!


> On Monday, 30 May 2016, 23:37, shad  wrote:
> Hello,


[...]

> the device will be able to control the tape speed and to sample with ADC> and 
> DAC the analog signals on the read / write heads, transferring the bare
> samples with almost no filtering to a PC.


When I was fiddling with the tape drives in my 11/730, I pulled the 

8155 from the controller board so I could control the tape motion 

by pulling signals low with wire links, I then hung a 'scope off the
output of the read amplifier. I found that most (old, defective) tapes
gave a very weak singnal, and that the flux transitions wrre almost 

equally spaced. I think you would not be able to recover anything from
that. But you can but try.


As an aside, I assume you've looked at the DEC data recovery circut. It's
clever. It's almost indpendant of tape speed. Basically, ramp up on the 

transition at the start of a bit cell, change to ramp down on the second
transition, then sample and reset, and start to ramp up again on the 

transition at the start of the next bit cell. Depending on whether the 

sample at the end of a bit cell is +ve or -ve it sees if it's a 0 or 1 


[...]
> But I have to fix the capstan too...


Now that I have done. I started off with aluminium alloy rpd (I think
1/2" diameter, but I can check my notes), turned it down, turned a 

groove for an o-ring, drilled the centre hole (oddly for a US machine
this is 3mm, not 1/8" -- and note the motor has different diameter 

spindles on the 2 ends!) drilled and tapped for the grub screw. With
a good tape I get a good, stead signal at the right speed at the output
of the read amplifier.


-tony

Re: TU58 yet one more time

[Mattis Lind]

tisdag 31 maj 2016 skrev shad :

> Hello,
> I'm very interested on TU58, as I have a lot of tapes that I need to dump,
> plus I would create some new (console at start) for my vax 730.

Great!  That is exactly what I want to do. But I also like to recover other
tapes from for example HP 9825 / HP 2645. I have studied the QIC-117 spec
some more but concluded that the drive is not dumb enough. The forward
physical and rewind physical only work with full speed and it isn't
specified if any data is output during these commands. However if one
sacrifice the entire drive and just use the mechanics it would be really
dumb so that could be a route. Formatting wouldn't work using this type of
drive since the width of the magnetic head is different.



> What I'm trying to do: use a drive mechanism connected with to modern mixed
> signal microcontroller with USB port.
> The device will be able to control the tape speed and to sample with ADC
> and DAC the analog signals on the read / write heads, transferring the bare
> samples with almost no filtering to a PC.


The bit period is 41.2 us nominally and it is using 1/3 2/3 encoding which
means that there are two flux transitions per bit one at the start and one
at either 1/3 or 2/3 of the bit. So I guess that to decode it one would
like to have at least 2 samples per each third or 6 samples per bit. That
would mean around 160 kHz sampling rate.


For writing I think that it is more on/off switching of a couple of
transistors to have the flux go either way.


> Then all the processing can be done via software.
> In this way, a weak data track can be maybe recovered, and an empty tape
> can be formatted.
>

One thing to think of is that a TU58 drive does not have optical BOT / EOT
detectors. They make use of special patterns on the tape for this. So to
format a blank tape can be a tricky operation, possibly manually
positioning the tape and then just write the nominal number of blocks and
hope the tape will be long enough.


> It's impossible to use the tape drive with a DEC machine or via serial
> port, but I'm not trying to emulate the standard TU58.
> If somebody is interested, I can share my ideas, I already begun with the
> hardware.
> But I have to fix the capstan too...
>

Looking forward hearing more about this!


>
> Andrea
>

/Mattis

Re: TU58 yet one more time

[shadoooo]

Hello,
I'm very interested on TU58, as I have a lot of tapes that I need to dump,
plus I would create some new (console at start) for my vax 730.
What I'm trying to do: use a drive mechanism connected with to modern mixed
signal microcontroller with USB port.
The device will be able to control the tape speed and to sample with ADC
and DAC the analog signals on the read / write heads, transferring the bare
samples with almost no filtering to a PC.
Then all the processing can be done via software.
In this way, a weak data track can be maybe recovered, and an empty tape
can be formatted.
It's impossible to use the tape drive with a DEC machine or via serial
port, but I'm not trying to emulate the standard TU58.
If somebody is interested, I can share my ideas, I already begun with the
hardware.
But I have to fix the capstan too...

Andrea

Re: TU58 yet one more time

[Mark J. Blair]

> On May 30, 2016, at 15:37, shad  wrote:
> 
> If somebody is interested, I can share my ideas, I already begun with the
> hardware.

Yes, please do share!

-- 
Mark J. Blair, NF6X 
http://www.nf6x.net/

Re: TU58 yet one more time.

[Mattis Lind]

2016-05-29 20:34 GMT+02:00 Mark J. Blair :

> My first attempt to use silicone tubing to repair my TU58 rollers was also
> unsuccessful. Maybe the material I used is too soft? Your experience
> suggests to me that I should hook up an oscilloscope to measure bit timing,
> and then adjust the roller composition and diameter to arrive close to the
> correct bit length.
>

It might be too soft. But the capstan doesn't look to flat when the tape is
inserted. So I am not sure.  Pin 5 on the 8085 has the read data and pin 7
is the strobe data.

Another question is how sensitive it is to speed variations. Apparently it
is. Or my tapes are bad. But I cannot tell for sure since I have no working
reference.

The encoding scheme is rather simple. And decoding is done by some analogue
electronics doing integration. Since it is a fixed capacitor value used it
can be problematic.

/Mattis



>
>
> --
> Mark J. Blair, NF6X 
> http://www.nf6x.net/
>
>

RE: TU58 yet one more time.

[Paul Birkel]

-Original Message-
From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Al Kossow
Sent: Sunday, May 29, 2016 3:00 PM
To: cctalk@classiccmp.org
Subject: Re: TU58 yet one more time.

On 5/29/16 11:34 AM, Mark J. Blair wrote:
> My first attempt to use silicone tubing to repair my TU58 rollers was also
unsuccessful. Maybe the material I used is too soft? Your experience
suggests to me that I should hook up an oscilloscope to measure bit timing,
and then adjust the roller composition and diameter to arrive close to the
correct bit length.
> 
> 

dug this up from the cctlk archive


--

http://www.usplastic.com/catalog/item.aspx?itemid=23485
It just says "norprene A-60-F" the outside.  It measures 3/8" I.D.

I think other's have said 7/16" i.d., but I could not find that.  I know I
bought it from US Plastics and it's A-60-F.
You have to buy 10' but its not very expensive.

-brad

-

"A-60-F" would be here?
http://www.usplastic.com/catalog/item.aspx?itemid=23886  $26.95 for 10 foot
length.  Ouch!

3/8" ID x 5/8" OD x 1/8" Wall TygonR A-60-F Hot Food & Beverage Tubing

-

Re: TU58 yet one more time.

[Mattis Lind]

2016-05-29 20:10 GMT+02:00 Al Kossow :

>
>
> On 5/29/16 10:03 AM, Mattis Lind wrote:
>
> > Would it be possible to use a Floppy Tape (QIC-117) tape drive to read
> > them?
>
> No. The heads are movable on floppy tapes, and the format is completely
> different.
>

Yes. I am aware of that. But that also means that the head can be moved
into the spot where the information is recorded. My quick reading of the
QIC-117 spec give that the one control the drive with a quite weird
interface consisting of the STEP, TRACK ZERO and INDEX lines.

The READ DATA is supposed to be the actual flux transitions. Likewise is
WRITE DATA.

What is not yet clear to me is whether that the QIC-117 drive is rather
dumb and leaves most work to the FDC or if it includes a lot of logic to
handle the reading process.
http://www.qic.org/html/standards/11x.x/qic117j.pdf

The QIC36 drive that was used to recover the information stored on the
Zilog S8000 tapes is completely stupid. The read data just reflected the
flux transitions which AJ recorded using a logic analyzer so that it was
possible to decode the MFM data stream in software. The tracks of course
also differed since the QIC36 drive was 9 track while the DEI drive used
for recording the S8000 tapes used four (fixed) heads. But nevertheless it
was possible to recover the entire tape thanks to the circuitry that AJ
devised to control the head position. Using a more modern SCSI drive it
will not be possible to read these tapes since they only handle GCR
encoding (as does QIC02 drives)


Could this kind of operation be done with a QIC-117. I.e. is the drive
stupid enough? Reading more of the spec may indicate that "segment" concept
might be the culprit that makes it non-feasible. It could be that the drive
keeps track of the segments somehow.

Of course there is always the possibility of "hacking" the drive. But then
it would help with schematics which is probably not available for these
quite "modern" things.

All input appreciated!


> If you send me your address, I can send you a chunk of tubing that Brad
> Parker and I
> have used to repair the drive wheels.
>

That would be very nice. Send you a message off-list.

/Mattis

Re: TU58 yet one more time.

[Al Kossow]

On 5/29/16 11:34 AM, Mark J. Blair wrote:
> My first attempt to use silicone tubing to repair my TU58 rollers was also 
> unsuccessful. Maybe the material I used is too soft? Your experience suggests 
> to me that I should hook up an oscilloscope to measure bit timing, and then 
> adjust the roller composition and diameter to arrive close to the correct bit 
> length.
> 
> 

dug this up from the cctlk archive


--

http://www.usplastic.com/catalog/item.aspx?itemid=23485
It just says "norprene A-60-F" the outside.  It measures 3/8" I.D.

I think other's have said 7/16" i.d., but I could not find that.  I know I 
bought it from US Plastics and it's A-60-F.
You have to buy 10' but its not very expensive.

-brad

Re: TU58 yet one more time.

[Mark J. Blair]

My first attempt to use silicone tubing to repair my TU58 rollers was also 
unsuccessful. Maybe the material I used is too soft? Your experience suggests 
to me that I should hook up an oscilloscope to measure bit timing, and then 
adjust the roller composition and diameter to arrive close to the correct bit 
length.


-- 
Mark J. Blair, NF6X 
http://www.nf6x.net/

Re: TU58 yet one more time.

[Al Kossow]

On 5/29/16 10:03 AM, Mattis Lind wrote:

> Would it be possible to use a Floppy Tape (QIC-117) tape drive to read
> them?

No. The heads are movable on floppy tapes, and the format is completely 
different.

If you send me your address, I can send you a chunk of tubing that Brad Parker 
and I
have used to repair the drive wheels.

TU58 yet one more time.

[Mattis Lind]

I have been fiddling with a TU58-EX device, dual TU58 drives in a small box.

The capstans is replaced. I used silicone tubing which I glued on and then
sanded down a bit. PVC tubing in a  size that would fit seems to be
unavailable in Sweden.

The two capstans were a little bit different in diameter at first. Drive
one closer to 17 mm but drive zero around 16.5mm. Drive zero read 5 of 8
tapes (two more tapes had belt breakage). One tape gave "Invalid Directory"
in RT11 the two other gave "Error reading directory". On drive one just one
tape was readable.

So the decision was to get closer to the nominal 5/8" (which I read was the
OD in a post by Tony Duell). With both drives at 16mm drive zero still read
the same amount of tapes and drive one read the same tapes plus one more
which was not readable on drive zero.

Highly annoying. So I decided to read more on the TU58. The spec says that
the bit time is 41.2 us. When I measure I get reading of between 42 and 44
us. (Yes I should have measured before trimming the capstans). So now the
tape is too slow. Although the OD is slightly above the nominal.

Is silicone tubing too soft?

Having been working on a project to recover a tape from a Zilog S8000
machine together with AJ (http://mightyframe.blogspot.se/) I just thought
that it might be possible to read the TU58 and HP DC100 tapes with some
other hardware doing post processing in a regular Linux box.

Would it be possible to use a Floppy Tape (QIC-117) tape drive to read
them? It appears that the tapes are not identical in size. A DC1000 is 0.25
" while the DC100 is 0.15". The capstan position would also differ. Are
there other physical differences that I am not aware off?

Since the TU58 drive is not able to format a tape it could be useful to
also write a new tape with TU58 format. But I guess that there are
difference in coercivity between different tapes.

I have read that Rik Bos successfully converted HP85 drives to take DC1000
tapes by modifying the capstan and changing the write current.

Before I go ahead buying some old Colorado T1000 drive dirt cheap I just
like to ask if this project is doomed because of whatever reason.

/Mattis